Surgical device with an end-effector assembly and system for monitoring of tissue during a surgical procedure

ABSTRACT

A medical instrument is provided and includes a housing and a shaft coupled to the housing. The shaft has a proximal end and a distal end. An end-effector assembly is disposed at the distal end of the shaft. The end-effector assembly includes first and second jaw members. At least one of the first and second jaw members is movable from a first position wherein the first and second jaw members are disposed in spaced relation relative to one another to at least a second position closer to one another wherein the first and second jaw members cooperate to grasp tissue therebetween. The medical instrument also includes one or more light-emitting elements and one or more light-detecting elements configured to generate one or more signals indicative of tissue florescence. The one or more light-emitting elements are adapted to deliver light energy to tissue grasped between the first and second jaw members.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.14/892,359 filed Nov. 19, 2015, which is a national stage applicationunder 35 U.S.C. § 371 of International PCT/US2014/040505 filed on Jun.2, 2014, which claims priority to, and the benefit of, U.S. ProvisionalApplication Ser. No. 61/829,420, filed on May 31, 2013, and U.S.Provisional Application Ser. No. 61/839,606, filed on Jun. 26, 2013. Theentire disclosures of the foregoing applications are incorporated byreference herein.

BACKGROUND Technical Field

The present disclosure relates to surgical forceps having components totreat tissue and/or monitor tissue treatment. More particularly, thepresent disclosure relates to open or endoscopic surgical forcepsadapted to treat tissue and/or to sense tissue properties, and methodsand systems for monitoring (e.g., optical, thermal, and/or electrical)of tissue during a surgical procedure.

Description of Related Art

In many surgical procedures, body vessels, e.g., blood vessels, ducts,adhesions, fallopian tubes, or the like are sealed to defunctionalize orclose the vessels. Traditionally, staples, clips or sutures have beenused to close a body vessel. However, these traditional procedures oftenleave foreign body material inside a patient. In an effort to reduceforeign body material left within the patient and to more effectivelyseal the body vessel, energy techniques that seal or fuse tissue byheating the tissue have been employed.

The process of radio-frequency (RF) tissue fusion involves clamping thetissue between two electrodes while holding opposing tissue faces underpressure. A controlled RF voltage is then applied so that the RF currentgenerates heat, and tissue transformations such as denaturation anddehydration are induced by the combined heat and pressure.

Endoscopic or open forceps are particularly useful for sealing sinceforceps utilize mechanical action to constrict, grasp, dissect and/orclamp tissue. Current vessel-sealing procedures utilize RF treatment toheat and desiccate tissue causing closure and sealing of vessels ortissue. Other treatment methods are known in the art; however, very fewsurgical instruments have the capability to treat tissue and monitortissue treatment without the use of additional surgical instruments.

SUMMARY

Tissue variability is a key challenge in energy-based therapies andsurgical procedures with energy-based devices. Improved treatmentmethods may depend on a better understanding of the tissue modificationsthat occur, not only allowing the development of effectiveenergy-delivery strategies but also enabling real-time feedback controlto control the tissue fusion procedure.

In accordance with an aspect of the present disclosure, a medicalinstrument is provided. The medical instrument includes a housing and ashaft coupled to the housing. The shaft has a proximal end and a distalend. An end-effector assembly is disposed at the distal end of theshaft. The end-effector assembly includes first and second jaw members.At least one of the first and second jaw members is movable from a firstposition wherein the first and second jaw members are disposed in spacedrelation relative to one another to at least a second position closer toone another wherein the first and second jaw members cooperate to grasptissue therebetween. The medical instrument also includes one or morelight-emitting elements coupled to either one or both of the first andsecond jaw members. The one or more light-emitting elements are adaptedto deliver light energy to tissue grasped between the first and secondjaw members. The medical instrument also includes one or morelight-detecting elements configured to generate one or more signalsindicative of tissue florescence.

In accordance with another aspect of the present disclosure, a medicalinstrument is provided and includes a housing, a shaft coupled to thehousing, and an end-effector assembly disposed at the distal end of theshaft. The end-effector assembly includes first and second jaw members.At least one of the first and second jaw members is movable from a firstposition wherein the first and second jaw members are disposed in spacedrelation relative to one another to at least a second position closer toone another wherein the first and second jaw members cooperate to grasptissue therebetween. The medical instrument also includes one or morelight-emitting elements coupled to either one or both of the first andsecond jaw members. The one or more light-emitting elements are adaptedto deliver light energy to tissue grasped between the first and secondjaw members. The medical instrument also includes a controllerconfigured to control energy delivered to tissue based on the one ormore signals indicative of tissue florescence.

In accordance with another aspect of the present disclosure, a systemfor treating tissue is provided and includes a medical instrument. Themedical instrument includes a housing and a shaft coupled to thehousing. The shaft has a proximal end and a distal end. An end-effectorassembly is disposed at the distal end of the shaft. The end-effectorassembly includes first and second jaw members. At least one of thefirst and second jaw members is movable from a first position whereinthe first and second jaw members are disposed in spaced relationrelative to one another to at least a second position closer to oneanother wherein the first and second jaw members cooperate to grasptissue therebetween. A first tissue-contacting surface is associatedwith the first jaw member. A second tissue-contacting surface isassociated with the second jaw member. One or more light-emittingelements are coupled to one or both of the first and second jaw members.The one or more light-emitting elements are adapted to deliver lightenergy to tissue grasped between the first and second jaw members. Themedical instrument includes one or more light-detecting elementsconfigured to sense one or more properties of the light energy passingthrough the tissue, and a controller coupled to the one or morelight-detecting elements and the one or more light-emitting elements.The controller is configured to control energy delivered to tissuedisposed between the first and second tissue-contacting surfaces duringactivation based on the one or more properties of the light energysensed by the one or more light-detecting elements.

In accordance with another aspect of the present disclosure, a method oftreating tissue is provided and includes positioning an end-effectorassembly including first and second jaw members at a first positionwithin tissue. Each of the first and second jaw members includes atissue-contacting surface. At least one of the first and second jawmembers is movable from a spaced relation relative to the other jawmember to at least one subsequent position wherein the tissue-contactingsurfaces cooperate to grasp tissue therebetween. The method alsoincludes activating a light-emitting element associated with one or bothof the first and second jaw members to emit light into tissue andevaluating one or more characteristics of the tissue based on a responseto light entering the tissue.

As used herein, the term “treat” refers to performing a surgicaltreatment to tissue including, but not limited to heating, sealing,cutting, sensing and/or monitoring. As used herein, the term “lightenergy source” refers broadly to include all types of devices thatproduce light for medical use (e.g., tissue treatment). These devicesinclude lasers, light-emitting diodes (LEDs), lamps, and other devicesthat produce light anywhere along an appropriate part of theelectromagnetic spectrum (e.g., from infrared to ultraviolet). It isalso to be understood that the light sources disposed herein may be usedinterchangeably, such that, if an LED light source is disclosed, a laserlight source may also be used, unless stated otherwise.

Various embodiments of the present disclosure provide systems andmethods for treating tissue (and/or monitoring of tissue) by deliveringlight thereto. This may be accomplished by placing a light source inintimate contact with the target tissue. In some embodiments, it may beaccomplished by connecting a light source to the target tissue with anoptical system designed to transmit the light from the light source tothe tissue. Either system may include elements that shape thedistribution of optical energy as it impinges on and interacts with thetarget tissue. As herein, the term “light-emitting elements” denotes anydevice from which light exits prior to interacting with the targettissue including but not limited to: light sources; the end of a lighttransmission system terminating at the target tissue; and/or refracting,diffracting, transmitting or reflecting optical elements such as lenses,diffraction gratings, windows and mirrors, and combinations thereof.

In general, the term “laser light source” is interchangeable, in thisdisclosure, with the terms “laser source,” “excitation light source” and“excitation source.” Laser light sources may produce light having awavelength from about 200 nanometers (nm) to about 15,000 nm and includebut are not limited to ruby lasers, tunable titanium-sapphire lasers,copper vapor lasers, carbon dioxide lasers, alexandrite lasers, argonlasers such as argon fluoride (ArF) excimer lasers, argon-dye lasers,potassium titanyl phosphate (KTP) lasers, krypton lasers such as kryptonfluoride (KrF) excimer lasers, neodymium:yttrium-aluminum-garnet(Nd:YAG) lasers, holmium:yttrium-aluminum-garnet (Ho:YAG) lasers,erbium:yttrium-aluminum-garnet (Er:YAG) lasers, diode lasers, fiberlasers, xenon chloride (XeCl) excimer lasers, tunable thalium lasers,and combinations thereof. Additional light source types also includefiber optic light sources and deuterium light sources.

In some aspects of the present disclosure, light may be generated atmultiple wavelengths. For example, Nd:YAG and KTP lasers may be part ofa single light source. Nd:YAG with a greater optical depth in tissue maybe used for sealing, and KTP with a shorter optical depth may be usedfor sealing smaller vessels, thinner tissue, or for cutting. As usedherein, the term “receiving module” refers to a component or apparatushaving the capability of receiving and/or sensing a signal (e.g., lightenergy and heat energy) and generating an output signal (e.g.,indication to a user, control information, parameter settinginstruction, etc.). This may occur by analyzing the received signal togenerate one or more control signals. In some embodiments, based on theone or more control signals, a controller may adjust operatingparameters of an energy source (e.g., laser source, RF generator, etc.)and/or perform other control functions, alarming functions, or otherfunctions in association therewith. The receiving module may alsotransmit the received signal to some other suitable component (e.g.,processor, signal analyzing unit, and/or generator) for signalprocessing, analysis, etc.

As described in more detail below with reference to the accompanyingfigures, the present disclosure generally relates to surgicalenergy-based devices that include an end-effector assembly configured tofuse (e.g., seal) and/or separate (e.g., cut) tissue. The presentdisclosure also provides one or more devices configured to sense and/ormonitor tissue and/or energy properties (e.g., tissue impedance, tissuetemperature, and tissue fluorescence) at various stages of treatment todetermine when the treatment is complete, efficacy of a tissue seal,and/or to measure jaw pressure. Optical sensing provides a betterindication of seal quality than existing methods such as electricalimpedance measurements. In some embodiments, tissue separation may beaccomplished with the same light energy device used for tissue sealing,which eliminates the need for a separate mechanical blade that istraditionally used for tissue separation in jaw members. The presentdisclosure also provides methods for providing feedback to the user,generator, controller and/or control algorithm with regard totemperature of tissue, electrical impedance of tissue, temporal profileof tissue fluorescence features, jaw closure pressure, jaw positioning,and/or other various feedback information, e.g., using Ramanspectroscopy, Raman maps, fluorescence spectroscopy, and/orlaser-induced tissue fluorescence. In some embodiments, fluorescencedata may be used for optimization of the RF energy delivery protocol toavoid excessive tissue thermal damage and/or incomplete tissue fusions.

Any of the following aspects and components thereof of the presentdisclosure may be interchangeably combined with one or more otherembodiments. For example, various disclosed methods and systems formonitoring of tissue and control processes may be utilized with variousjaw member embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently-disclosed surgical device with anend-effector assembly and the method and system for monitoring of tissueduring a surgical procedure will become apparent to those of ordinaryskill in the art when descriptions of various embodiments thereof areread with reference to the accompanying drawings, of which:

FIG. 1A is a perspective view of an endoscopic forceps having anend-effector assembly coupled to the distal end of the forceps inaccordance with an embodiment of the present disclosure;

FIG. 1B is a perspective view of an open forceps having a handleassembly and an end-effector assembly coupled to the distal end of thehandle assembly in accordance with an embodiment of the presentdisclosure;

FIG. 2A is a side, cross-sectional view of an end-effector assembly inaccordance with an embodiment of the present disclosure;

FIG. 2B is a front, cross-sectional view of the end-effector assembly ofFIG. 2A;

FIG. 3 is a front, cross-sectional view of an end-effector assembly inaccordance with another embodiment of the present disclosure;

FIG. 4A is a side, cross-sectional view of an end-effector assembly inaccordance with another embodiment of the present disclosure;

FIG. 4B is a front, cross-sectional view of the end-effector assembly ofFIG. 4A;

FIG. 4C is a side, schematic view of a laser fiber of the end-effectorassembly of FIG. 4A;

FIG. 5 is a front, cross-sectional view of an end-effector assembly inaccordance with another embodiment of the present disclosure;

FIG. 6 is a side, cross-sectional view of an end-effector assembly inaccordance with another embodiment of the present disclosure;

FIGS. 7A and 7B are side, cross-sectional views of an end-effectorassembly in accordance with another embodiment of the presentdisclosure;

FIG. 8A is a side, cross-sectional view of an end-effector assemblyaccording to another embodiment of the present disclosure;

FIGS. 8B and 8C are top views of the end-effector assembly shown in FIG.8A;

FIG. 9A is a top view of a jaw member including a light dissectionelement disposed on an outer periphery thereof in accordance with anembodiment of the present disclosure;

FIG. 9B is a front, cross-sectional of a jaw member including a lightdissection element disposed on an outer periphery thereof in accordancewith an embodiment of the present disclosure;

FIG. 10 is a side, cross-sectional view of an end-effector assembly inaccordance with another embodiment of the present disclosure;

FIG. 11 is a schematic diagram of a surgical system in accordance withan embodiment of the present disclosure;

FIG. 12 is a plot of absorption coefficient versus wavelength of tissueconstituents in accordance with an embodiment of the present disclosure;

FIG. 13 is an illustrative representation of porcine blood vessel tissuein accordance with an embodiment of the present disclosure;

FIGS. 14A through 14C are Raman maps of the indicated regions shown inFIG. 13 according to an embodiment of the present disclosure;

FIG. 15 is an illustrative representation of porcine bowel tissue inaccordance with an embodiment of the present disclosure;

FIGS. 16A through 16C are Raman maps of the indicated regions shown inFIG. 15 in accordance with an embodiment of the present disclosure;

FIG. 17 is an illustrative representation of porcine bowel tissue inaccordance with an embodiment of the present disclosure;

FIGS. 18A through 18C are Raman maps of the indicated regions shown inFIG. 17 in accordance with an embodiment of the present disclosure;

FIG. 19 is an illustrative representation of porcine bowel tissue inaccordance with an embodiment of the present disclosure;

FIGS. 20A through 20C are Raman maps of the indicated regions shown inFIG. 19 in accordance with an embodiment of the present disclosure;

FIG. 21 is a graph illustrating mean Raman spectra of healthy and fusedtissue areas mapped in porcine blood vessel and bowel tissue inaccordance with an embodiment of the present disclosure;

FIG. 22A is graph illustrating a fused porcine blood vessel inaccordance with an embodiment of the present disclosure;

FIG. 22B is graph illustrating fused porcine bowel tissue withoutcompression in accordance with an embodiment of the present disclosure;

FIG. 22C is graph illustrating porcine bowel tissue fused at 0.2 MPacompression pressure in accordance with an embodiment of the presentdisclosure;

FIG. 23A is an illustrative representation of a histological section ofa fused porcine blood vessel sample in accordance with an embodiment ofthe present disclosure;

FIG. 23B is an illustrative representation of a histological section ofa porcine small-bowel sample fused at 0 MPa in accordance with anembodiment of the present disclosure;

FIG. 23C is an illustrative representation of a histological section ofa porcine small-bowel sample fused at 0.2 MPa in accordance with anembodiment of the present disclosure;

FIG. 23D is an illustrative representation of a histological section ofa porcine small-bowel sample fused at 0.3 MPa in accordance with anembodiment of the present disclosure;

FIG. 24 is a graph of burst pressure test results versus fusioncompression pressure in accordance with an embodiment of the presentdisclosure;

FIG. 25A is an illustrative representation of stained histology imagesfor fused samples cut transversally across the fusion line in accordancewith an embodiment of the present disclosure;

FIG. 25B is an illustrative representation of stained histology imagesfor fused samples cut parallel to the fusion line according to inaccordance with an embodiment of the present disclosure;

FIGS. 26A through 26D are graphs illustrating mean excitation spectrawith standard deviation for “well-fused” versus “poorly fused” versus“control” samples in accordance with embodiments of the presentdisclosure;

FIGS. 27A through 27D are boxplots for Kurskal-Wallis testing results inaccordance with embodiments of the present disclosure;

FIG. 28 is a schematic illustration of a system in accordance with anembodiment of the present disclosure;

FIGS. 29A through 29C are plots for fusion testing results in accordancewith an embodiment of the present disclosure;

FIGS. 30A through 30C are plots for fusion testing results in accordancewith an embodiment of the present disclosure; and

FIG. 31 is an illustration of a real-time multi-wavelength laser-inducedfluorescence spectroscopy system in accordance with an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of surgical devices with an end-effectorassembly and methods and systems for monitoring of tissue during asurgical procedure of the present disclosure are described withreference to the accompanying drawings. Like reference numerals mayrefer to similar or identical elements throughout the description of thefigures. As shown in the drawings and as used in this description, andas is traditional when referring to relative positioning on an object,the term “proximal” refers to that portion of the apparatus, orcomponent thereof, closer to the user and the term “distal” refers tothat portion of the apparatus, or component thereof, farther from theuser.

This description may use the phrases “in an embodiment,” “inembodiments,” “in some embodiments,” or “in other embodiments,” whichmay each refer to one or more of the same or different embodiments inaccordance with the present disclosure.

As it is used in this description, “transmission line” generally refersto any transmission medium that can be used for the propagation ofsignals from one point to another. A transmission line may be, forexample, a wire, a two-wire line, a coaxial wire, a waveguide, a fiberoptic line and/or fiber optic bundles.

As it is used herein, “computer” generally refers to anything thattransforms information in a purposeful way. Examples of a computer mayinclude: a computer; a personal computer (PC); a portable computer; alaptop computer; a computer having a single processor, multipleprocessors, or multi-core processors, which may operate in paralleland/or not in parallel; a general purpose computer; a supercomputer; amainframe; a super mini-computer; a mini-computer; a workstation; amicro-computer; a server; a web appliance; a hybrid combination of acomputer and an interactive television; a tablet personal computer; apersonal digital assistant (PDA); application-specific hardware toemulate a computer and/or software, such as, for example, a digitalsignal processor (DSP), a field-programmable gate array (FPGA), anapplication specific integrated circuit (ASIC), an application specificinstruction-set processor (ASIP), a chip, chips, or a chip set; a systemon a chip (SoC), or a multiprocessor system-on-chip (MPSoC); an opticalcomputer; a quantum computer; a biological computer; and an apparatusthat may accept data, may process data in accordance with one or morestored software programs, and may generate results. For the purposes ofthis description, the terms “software” and “code” should be interpretedas being applicable to software, firmware, or a combination of softwareand firmware.

Various embodiments of the present disclosure provide surgicalinstruments suitable for sealing, cauterizing, coagulating, desiccating,and/or cutting tissue, e.g., vessels and vascular tissue, during asurgical procedure. Embodiments of the presently-disclosed surgicalinstruments may be configured to provide light energy, which may besuitable for sealing, cauterizing, coagulating, desiccating, and/orcutting tissue. The light energy may be provided in different forms,including but not limited to lasers, light-emitting diode, and any othersuitable type of light energy. Embodiments of the presently-disclosedsurgical instruments may be configured to provide monopolarelectrosurgical energy and/or bipolar electrosurgical energy, which maybe suitable for sealing, cauterizing, coagulating, desiccating, and/orcutting tissue, e.g., vessels and vascular tissue. Embodiments of thepresently-disclosed surgical instruments may be suitable for utilizationin endoscopic surgical procedures and/or suitable for utilization inopen surgical applications.

Embodiments of the presently-disclosed surgical instruments may beimplemented using a variety of types of energy, e.g., surgical energy atradio frequencies (RF) and/or at other frequencies, optical, and/orthermal energy. Embodiments of the presently-disclosed surgicalinstruments may be configured to be connectable to one or more energysources, e.g., laser sources, RF generators, and/or self-contained powersources. Embodiments of the presently-disclosed surgical instruments maybe connected through a suitable bipolar cable and/or other transmissionline to an electrosurgical generator and/or other suitable energysource, e.g., laser light source.

The Raman spectroscopy method described herein provides direct insightsinto tissue constituent and structure changes on the molecular level,exposing spectroscopic evidences of the migration of collagen fibersbetween tissue layers as well as the denaturing of collagen andrestructuring of collagen crosslinks post fusion. Various embodimentsdescribed herein utilize these insights to provide a betterunderstanding of the intrinsic mechanisms for tissue fusion and toprovide optical feedback-control methods for heat-induced tissue fusionand improved control methods for tissue fusion procedures in accordancewith the present disclosure.

The real-time multi-wavelength laser-induced fluorescence spectroscopysystem described herein

FIG. 1A depicts an embodiment of a forceps for use in connection withendoscopic surgical procedures, and an embodiment of an open version ofa forceps is shown in FIG. 1B.

For the purposes herein, either an endoscopic instrument or an opensurgery instrument may be utilized with any of the embodiments ofend-effector assemblies described herein. It should be noted thatdifferent electrical, optical and mechanical connections and otherconsiderations may apply to each particular type of instrument. However,aspects with respect to the end-effector assembly and the operatingcharacteristics thereof remain generally consistent with respect to boththe endoscopic or open surgery designs.

Various embodiments of the present disclosure provide an apparatus,system and method for sealing tissue using light energy. Light (e.g.,with a wavelength range of from about 200 nm to about 11,000 nm) is usedto heat tissue due to the absorption of light into the tissue.Absorption, transmittance, and scattering of light energy depends on thetissue, the state of the tissue (e.g., hydration, disease state,treatment stage, etc.), and the wavelength of the light. In accordancewith some embodiments of the present disclosure, these factors areutilized to control the distribution of the energy within the tissuebased on an appropriate choice of the wavelength. More specifically,wavelengths that are strongly absorbed by the tissue deposit energycloser to the surface of the tissue, and wavelengths that are weaklyabsorbed by the tissue are used to deposit a larger fraction of theincident energy deeper in the tissue. In particular, since tissue isrelatively transparent to light at certain infrared wavelengths, lightenergy at infrared frequencies may be used for deeper energy deposition.

In FIGS. 1A and 1B, surgical instruments (generally referred to hereinas forceps 10 and open forceps 10′) are shown for use with varioussurgical procedures. Forceps 10 and open forceps 10′ may includeadditional, fewer, or different components than shown in FIGS. 1A and1B, depending upon a particular purpose or to achieve a desired result.

Forceps 10 includes a transmission line 34, which may connect directlyto a light energy source (e.g., energy source 40) for generating lightenergy adapted to treat tissue. Transmission line 34 (also referred toherein as “cable 34”) may be formed from a suitable flexible,semi-rigid, or rigid cable. Cable 34 may be internally divided into oneor more cable leads (not shown) each of which transmits energy throughtheir respective feed paths to the end-effector assembly 100. Cable 34may additionally, or alternatively, include an optical fiber configuredto transmit light energy and/or control signals to the end-effectorassembly 100.

Energy source 40 may be any generator suitable for use with surgicaldevices, and may be configured to output various types of energy, e.g.,light energy having a wavelength from about 200 nm to about 11,000 nm.Energy source 40 may additionally, or alternatively, be configured toprovide RF energy and/or various frequencies of electromagnetic energy.

Energy source 40 may include any laser light source suitable for usewith surgical devices. In some embodiments, more than one laser sourcemay be included in the energy source 40, and more than one laser may beused during a surgical procedure. Examples of laser light sourcesinclude Thorlabs' diode lasers modules (Thorlabs Inc., Newton, N.J.).Energy source 40 shown in FIG. 1 includes a controller 42, e.g., logiccircuit, computer, processor, field programmable gate array, and thelike. Controller 42 may include a microprocessor having a memory (notexplicitly shown), which may be volatile type memory (e.g., RAM) and/ornon-volatile type memory (e.g., flash media, disk media, etc.).

In some embodiments, the controller 42 is configured to provide timing,wavelength, and/or power control of the one or more lasers. Energysource 40 may include one or more mechanisms for laser selection,filtering, temperature compensation, and/or Q-switching operations. Insome embodiments, the energy source 40 may include a function generatorand optical shutter used to modulate a continuous-wave laser to generatepulsed output. Various embodiments of the forceps 10 utilizing theaforementioned light energy are discussed in more detail below.

In some embodiments, wherein the energy source 40 is configured toprovide RF energy, the controller 42 may additionally, or alternatively,utilize one or more signals indicative of conditions and/or operationalparameters (e.g., tissue impedance, temperature, jaw member openingangle, force applied to tissue, thickness of tissue, and/or and tissuefluorescence) to adjust one or more operating parameters associated withthe energy source 40 (e.g., duration of application of RF energy, modeof operation, power, current, and voltage) and/or instruct the energysource 40 to perform other control functions, alarming functions, orother functions in association therewith. Examples of generators thatmay be suitable for use as a source of RF energy are commerciallyavailable under the trademarks FORCE EZ™, FORCE FX™, and FORCE TRIAD™offered by Covidien Surgical Solutions of Boulder, Colo.

Forceps 10 is configured to support an end-effector assembly (e.g.,end-effector assembly 100). Forceps 10 includes a housing 20, a handleassembly 22, a trigger assembly 25, a rotatable assembly 28, andend-effector assembly 100. End-effector assembly 100 may include anyfeature or combination of features of the jaw member embodimentsdisclosed herein. One or more components of the forceps 10, e.g.,housing 20, rotatable assembly 28, and/or end-effector assembly 100, maybe adapted to mutually cooperate to grasp, seal, divide and/or sensetissue, e.g., tubular vessels and vascular tissue. In some embodiments,trigger assembly 25 may be configured to actuate a cutting function ofthe forceps 10 or to actuate another component, as described in moredetail below.

End-effector assembly 100, which is described in more detail later inthis disclosure, generally includes two jaw members 110 and 120 disposedin opposing relation relative to one another. One or both of the jawmembers 110 and 120 are movable from a first position wherein the jawmembers 110 and 120 are disposed in spaced relation relative to oneanother to a second position wherein the jaw members 110 and 120cooperate to grasp tissue therebetween.

Forceps 10 includes an elongated shaft 12 having a distal portion 16configured to mechanically engage end-effector assembly 100. Theproximal end 14 of shaft 12 is received within housing 20, andconnections relating thereto are shown and described incommonly-assigned U.S. Pat. No. 7,150,097 entitled “Method OfManufacturing Jaw Assembly For Vessel Sealer And Divider,”commonly-assigned U.S. Pat. No. 7,156,846 entitled “Vessel Sealer AndDivider For Use With Small Trocars And Cannulas,” commonly-assigned U.S.Pat. No. 7,597,693 entitled “Vessel Sealer And Divider For Use WithSmall Trocars And Cannulas,” and commonly-assigned U.S. Pat. No.7,771,425 entitled “Vessel Sealer And Divider Having A Variable JawClamping Mechanism,” the disclosures of which are herein incorporated byreference in their entireties. Rotatable assembly 28 is mechanicallyassociated with shaft 12 such that rotational movement of rotatableassembly 28 imparts similar rotational movement to shaft 12 that, inturn, rotates end-effector assembly 100.

Handle assembly 22 includes a fixed handle 26 and a movable handle 24.In some embodiments, the fixed handle 26 is integrally associated withthe housing 20, and the movable handle 24 is selectively movablerelative to the fixed handle 26. Movable handle 24 of the handleassembly 22 is ultimately connected to the drive assembly (not shown).As can be appreciated, applying force to move the movable handle 24toward the fixed handle 26 pulls a drive sleeve (not shown) proximallyto impart movement to the jaw members 110 and 120 from an open position,wherein the jaw members 110 and 120 are disposed in spaced relationrelative to one another, to a clamping or closed position, wherein thejaw members 110 and 120 cooperate to grasp tissue therebetween. Examplesof handle assembly embodiments of the forceps 10 are described in theabove-mentioned, commonly-assigned U.S. Pat. Nos. 7,150,097, 7,156,846,7,597,693 and 7,771,425.

In some embodiments, the end-effector assembly 100 is configured as aunilateral assembly that includes a stationary jaw member (e.g., jawmember 120) mounted in fixed relation to the shaft 12 and a pivoting jawmember (e.g., jaw member 110) movably mounted about a pin 19. Jawmembers 110 and 120 may be curved at various angles to facilitatemanipulation of tissue and/or to provide enhanced line-of-sight foraccessing targeted tissues. Alternatively, the forceps 10 may include abilateral assembly, i.e., both jaw members 110 and 120 move relative toone another.

Jaw members 110 and 120, as shown for example in FIG. 2B, include atissue-contacting surface 112 and 122, respectively, arranged in opposedrelation relative to one another. Tissue-contacting surfaces 112 and 122cooperate to grasp and seal tissue held therebetween upon application ofenergy from energy source 40. In some embodiments, tissue-contactingsurfaces 112 and 122 are connected to the energy source 40 such thatlight energy can be transmitted to and/or through the tissue heldtherebetween.

First and second switch assemblies 30 and 32 are configured toselectively provide light energy to end-effector assembly 100. Moreparticularly, the first switch assembly 30 may be configured to performa first type of surgical procedure (e.g., seal, cut, and/or sense) and asecond switch assembly 32 may be configured to perform a second type ofsurgical procedure (e.g., seal, cut, and/or sense). It should be notedthat the presently-disclosed embodiments may include any number ofsuitable switch assemblies and are not limited to only switch assemblies30 and 32. It should further be noted that the presently-disclosedembodiments may be configured to perform any suitable surgical procedureand are not limited to only sealing, cutting and sensing.

Forceps 10 generally includes a controller 46. In some embodiments, asshown in FIG. 1, the controller 46 is formed integrally with the forceps10. In other embodiments, the controller 46 may be provided as aseparate component coupled to the forceps 10. Controller 46 may includeany type of computing device, computational circuit, or any type ofprocessor or processing circuit capable of executing a series ofinstructions that are stored in a memory. Controller 46 may beconfigured to control one or more operating parameters associated withthe energy source 40 based on one or more signals indicative of userinput, such as generated by the first and second switch assemblies 30and 32 and/or one or more separate, user-actuatable buttons or switches.Examples of switch configurations that may be suitable for use with theforceps 10 include, but are not limited to, pushbutton, toggle, rocker,tactile, snap, rotary, slide and thumbwheel. In some embodiments, theforceps 10 may be selectively used in either a monopolar mode or abipolar mode by engagement of the appropriate switch.

First and second switch assemblies 30 and 32 may also cooperate with thecontroller 42, which may be configured to automatically trigger one ofthe switches to change between a first mode (e.g., sealing mode) and asecond mode (e.g., cutting mode) upon the detection of one or moreparameters or thresholds. In some embodiments, the controller 42 (and/orthe controller 46) is configured to receive feedback information,including various sensor feedback with regard to temperature of tissue,electrical impedance of tissue, jaw closure pressure, jaw positioning,and/or other various feedback information, e.g., using Ramanspectroscopy, Raman maps, fluorescence spectroscopy, and/orlaser-induced tissue fluorescence, and to control the energy source 40based on the feedback information.

Embodiments of the present disclosure allow the jaw members 110 and 120to seal and/or cut tissue using light energy. In some embodiments, thecontroller 42 may include a feedback loop that indicates when a tissueseal is complete based upon one or more of the following parameters:tissue temperature, optical sensing, change in impedance of the tissueover time and/or changes in the optical or electrical power or currentapplied to the tissue over time, rate of change of these properties andcombinations thereof. An audible or visual feedback monitor may beemployed to convey information to the surgeon regarding the overall sealquality and/or the completion of an effective tissue seal.

Referring now to FIG. 1B, an open forceps 10′ is depicted and includesend-effector assembly 100 (similar to forceps 10) that is attached to ahandle assembly 22′ that includes a pair of elongated shaft portions 12a′ and 12 b′. Each elongated shaft portion, 12 a′ and 12 b′,respectively, has a proximal end 14 a′ and 14 b′, respectively, and adistal end 16 a′ and 16 b′, respectively. The end-effector assembly 100includes jaw members 110 and 120 coupled to distal ends 16 a′ and 16 b′of shafts 12 a′ and 12 b′, respectively. The jaw members 110 and 120 areconnected about pivot pin 19′ that allows jaw members 110 and 120 topivot relative to one another from the first to second positions fortreating tissue (as described above). Tissue-contacting surfaces 112 and122 are connected to opposing jaw members 110 and 120.

Each shaft 12 a′ and 12 b′ includes a handle 17 a′ and 17 b′,respectively, disposed at the proximal end 14 a′ and 14 b′ thereof.Handles 17 a′ and 17 b′ facilitate movement of the shafts 12 a′ and 12b′ relative to one another which, in turn, pivot the jaw members 110 and120 from the open position wherein the jaw members 110 and 120 aredisposed in spaced relation relative to one another to the clamping orclosed position wherein the jaw members 110 and 120 cooperate to grasptissue therebetween.

In some embodiments, one or both of the shafts, e.g., shaft 12 a′,includes a first switch assembly 30′ and a second switch assembly 32′.First and second switch assemblies 30′ and 32′ may be configured toselectively provide energy to the end-effector assembly 100. Moreparticularly, the first switch assembly 30′ may be configured to performa first type of surgical procedure (e.g., seal, cut, or sense) andsecond switch assembly 32′ may be configured to perform a second type ofsurgical procedure (e.g., seal, cut, or sense). In some embodiments,both or one of the shafts, e.g., shaft 12 b′, may include a triggerassembly 25′ for actuation of an additional laser fiber (e.g., laserfiber 230 a and/or 230 b shown in FIG. 3).

With continued reference to FIG. 1B, forceps 10′ is depicted having acable 34′ that connects the forceps 10′ to energy source 40. In someembodiments, cable 34′ is internally divided within the shaft 12 b′ totransmit light energy through various transmission paths to one or morecomponents of end-effector assembly 100.

FIGS. 2A and 2B illustrate an end-effector assembly 100 according to anembodiment of the present disclosure, which is configured for use witheither instrument 10 or instrument 10′, discussed above or any othersuitable surgical instrument. However, for purposes of simplicity andconsistency, end-effector assembly 100 is described hereinbelow withreference to instrument 10.

In some embodiments, as shown for example in FIGS. 2A and 2B, jawmembers 110 and 120 include proximal ends 110 a and 120 a, respectively,distal ends 110 b and 120 b, respectively, and a groove or channel 130and 140, respectively, defined therebetween. Jaw member 110 includes alight-diffusing element 132 that is disposed on or alongtissue-contacting surface 112. The light-diffusing element 132 may bemade from any suitable light diffusing material, such as frostedsapphire crystal. The light-diffusing element 132 is disposed withinchannel 130. Tissue-contacting surfaces 112 and 122 may include areflective surface disposed thereon. In some embodiments, the surfaceincludes, but is not limited to polished metal, coating or any othermaterial that is adapted to reflect light.

In other embodiments, tissue-contacting surfaces 112 and 122 may alsoinclude a coating or cover 112 a and 122 a. In some embodiments, thecoatings 112 a and 122 a may be formed from a light absorbing material(e.g., a light absorbent coating), a transparent material, a scatteringmaterial, or a reflective material. In some embodiments, the coating 112a may be formed from one material (e.g., a transparent material) whilethe coating 122 a may be formed from a different material (e.g., a lightabsorbent or reflective material). In some embodiments, the coatings 112a and 122 a may both be formed from the same material, such as areflective material. Providing both tissue-contacting surfaces 112 and122 with reflective surfaces increases absorption of the light beingsupplied to the tissue since the light passes multiple timestherethrough, which may shorten the treatment time.

In some embodiments, the coatings 112 a and 122 a may include a gel oranother biocompatible film disposed thereon. The gel or the film mayinclude a dye of a specific color designed to absorb light energy at aspecific wavelength. In some embodiments, the gel may be applied to thetissue prior to treatment.

In other embodiments, the coatings 112 a and 122 a are absorbentcoatings formed from a thermochromic material configured to increaseabsorption properties as temperature increases. As used herein, the term“thermochromic” generally refers to any material that changes color inresponse to a change in temperature. As the temperature of the jawmembers 110 and 120 increases during application of energy, theabsorbent coatings 112 a and 122 a become progressively more absorbingand provide more heat to the tissue.

The light-diffusing element 132 may be coupled to energy source 40 viacable 34, which may include one or more a light transporting or lightgenerating fibers therewithin. In some embodiments, the energy source 40is adapted to generate a light of a desired wavelength from about 200 nmto about 11,000 nm and transmit the light energy along cable 34 to theforceps 10, 10′ and, more specifically, to the light-diffusing element132.

Light-diffusing element 132 may have a substantially cylindrical orconical shape and may be formed from a suitable light conductingmaterial (e.g., sapphire crystal, crystal glass, plastic fiber, and thelike). More specifically, the light-diffusing element 132 may bemanufactured from any suitable laser or light conducting medium toobtain desired diffusion properties.

Groove 140 may be configured to fit around or about light-diffusingelement 132 when the jaw members 110 and 120 are disposed in a closedposition. Groove 140 may also have a reflective surface such that lightemitted from light-diffusing element 132 may pass through tissue andsubsequently be reflected back into tissue to form a desiredillumination pattern. In some embodiments, groove 140 may have lightabsorbing properties and/or include a material having light absorbingproperties (e.g., a light absorbent coating). In this manner, when lightis absorbed, groove 140 and/or the absorbent material may heat to asuitable temperature to operably treat tissue held between jaw members110 and 120.

During operation, once tissue is grasped between the tissue-contactingsurfaces 112 and 122, laser light is transmitted from the energy source40 to the light-diffusing element 132, which then emits light energyinto the tissue. Since the tissue-contacting surfaces 112 and 122 areadapted to reflect light, the light energy emitted by thelight-diffusing element 132 is concentrated in the volume between thejaw members 110 and 120 which in turn, heats up the tissue graspedtherebetween without compromising the surrounding tissue. After a presetduration or upon a signal from one or more sensors (described in furtherdetail below), the energy is terminated indicating that the tissuetreatment (e.g., seal or cutting) is complete.

Referring now to FIG. 3, another embodiment of the presently-disclosedend-effector assembly is shown as end-effector assembly 200.End-effector assembly 200 includes jaw members 210 and 220 havingtissue-contacting surfaces 212 and 222. Similar to the above discussedjaw members 110 and 120, jaw members 210 and 220 cooperate to grasptissue therebetween. Each jaw member 210 and 220 defines channels orgrooves disposed therealong. More specifically, jaw member 210 includesgrooves 230, 230 a, and 230 b, and jaw member 220 includes grooves 240,240 a, and 240 b. In some embodiments, jaw member 210 includes aplurality of laser light fibers (e.g., laser fiber 232, 234 a, and 234b) that span along the length of the jaw member 210 and withinrespective grooves 230, 230 a, and 230 b. The laser fibers areconfigured to emit a laser light between and along the length of jawmembers 210 and 220.

Jaw member 210 includes a centrally-positioned laser fiber 232 that isdisposed within channel 230. Alongside of channel 230, jaw member 210also defines channel or grooves 230 a and 230 b that are laterallypositioned from channel 230 and include peripheral laser fibers 234 aand 234 b. The laser fibers 234 a and 234 b may be configured forsealing tissue, based on the type of light energy supplied thereto,pressure applied to the jaw members 210 and 220, as well the reflectiveor absorbing properties of the grooves disposed about the fibers asdescribed in more detail below. In some embodiments, thetissue-contacting surfaces 212 and 222 may include a transparent coatingor cover disposed on the surface thereof, similar to thetissue-contacting surfaces 112 and 122 of FIGS. 2A and 2B. The laserfiber 232 may be configured to cut tissue after an effective seal hasbeen achieved by laser sealing fibers 234 a and 234 b. In someembodiments, cutting may be performed independent of the sealing. Inaddition, a reflective groove 240 may be disposed on the jaw member 220such that when laser light is emitted from laser fiber 232, the laserlight is reflected from reflective groove 240 back through tissueforming a desired illumination pattern. Additionally or alternatively,laser fibers 234 a and 234 b may also have respective reflective orabsorbing grooves 240 a and 240 b within opposing jaw member 220, asdescribed above.

It should be noted that any number of laser fibers may be used in any ofthe embodiments discussed in the present disclosure to achieve tissuesealing or cutting based on the light energy transmitted through thelaser fibers. Similarly, any number of laser cutting fibers (e.g., laserfiber 232) may be used in any of the embodiments discussed in thepresent disclosure. In some embodiments, a single laser fiber may alsobe configured to include sealing and cutting capabilities in any of theembodiments of the present disclosure. It should be noted that any oneof the laser fibers may be configured to transmit energy at differentwavelengths depending on the surgical treatment (e.g., sealing, cuttingand/or sensing). In other embodiments, a particular laser or light fibermay be configured to perform a particular surgical treatment (e.g.,sealing, cutting and/or sensing). One or more sensors may be employedand/or a feedback circuit may be integrated with respect to end-effectorassembly 200 to signal the user after an effective seal and/or effectiveseparation. An automated seal and cut algorithm may also be employed forthis purpose that uses a single activation of a switch, e.g., switch 32,to initiate the process.

FIGS. 4A through 4C illustrate an embodiment of an end-effector assembly300 that includes jaw members 310 and 320 having proximal ends 310 a,320 a, respectively, and distal ends 310 b, 320 b, respectively. Eachjaw member 310 and 320 has a tissue-contacting surface 312 and 322,respectively. In some embodiments, the tissue-contacting surfaces 312and 322 may include a transparent coating or cover disposed on thesurface thereof, similar to the tissue-contacting surfaces 112 and 122of FIGS. 2A and 2B. Additionally, jaw member 310 includes a channel orgroove 330 defined therealong that is configured to include a surgicaltreatment laser fiber 332 (e.g., sealing, cutting and/or sensing) havingproximal and distal ends 332 a and 332 b. Surgical treatment laser fiber332 is configured to translate along a longitudinal axis “X-X”, definedwithin jaw member 310, and within channel 330. For example, surgicaltreatment laser fiber 332 may be translated from proximal end 310 a todistal end 310 b of jaw member 310 (e.g., in a distal direction “A”) tocut, seal and/or sense tissue being grasped between jaw members 310 and320. Additionally or alternatively, surgical treatment laser fiber 332may be translated from distal end 310 b to proximal end 310 a of jawmember 310 (e.g., in a proximal direction “B”) to cut, seal and/or sensetissue being grasped therebetween. Surgical treatment laser fiber may bestationary within either one or both of the jaw members 310 and 320. Inother embodiments, any other suitable type of light energy, includingbut not limited to laser light energy, may be transmitted by theaforementioned fibers (and/or other fiber pathways).

Referring to FIGS. 4A through 4C, the distal end of laser fiber 332 bincludes a laser emitter 334 that is configured to emit a laser beaminto a defined solid angle 336 forming a desired illumination pattern.Laser fiber 332 may be a so-called “end-firing” or “side-firing” laserfiber. The term “end-firing” as used herein denotes a laser fiber thathas the capability to emit a light along a longitudinal axis “X-X”defined by jaw member 310. The term “side-firing” as used herein denotesa laser fiber that has the capability to emit light (or any othersuitable light energy) that is non-parallel to the longitudinal axis“X-X” of jaw member 310. Laser emitter 334 may include variouscomponents, such as one or more reflective surfaces (e.g., mirrors), oneor more optical fibers, one or more lenses, or any other suitablecomponents for emitting and/or dispersing a laser beam. Moreparticularly, laser emitter 334 is configured to emit light into thesolid angle 336 that has an outer boundary that may be variable orpredetermined. By varying or adjusting the solid angle 336, a lasertarget area 338 may be adjusted to vary the intensity of the laser lightenergy illuminating the tissue and the area of the tissue being treated,dissected or cut. Laser target area 338 may define any suitable targetshape, for example, but not limited to an ellipse, rectangle, square andtriangle. In some embodiments, laser emitter 334 may also be configuredto seal and/or cut tissue grasped between the jaw members.

In addition to longitudinal movement of the laser emitter 334 along thelongitudinal axis “X-X,” the laser emitter 334 may also be rotated aboutthe axis “X-X” and/or moved laterally (e.g., transverse) with respectthereto. Longitudinal, lateral, and rotational motion of the laseremitter 334 allows for directing light energy in any desired directionto accomplish desired tissue treatment effects.

Reflective groove(s) 340 may be made from a polished metal or a coatingmay be applied to the jaw member 320 if the jaw member 320 is formedfrom a non-metal and/or non-reflective material (e.g., plastic). Thereflective groove 340 reflects laser light back through the tissue.Laser emitter 334 may receive the reflected laser light and transmit thesignal back to energy source 40 for processing. Various types of datamay be integrated and calculated to render various outcomes or controltissue treatment based on the transmitted or reflected light.

FIG. 5 illustrates an embodiment of an end-effector assembly 400 forforming a desired illumination pattern. End-effector assembly 400includes jaw members 410 and 420 having tissue-contacting surfaces 412and 422. Similar to the above-described jaw members, jaw members 410 and420 cooperate to grasp tissue therebetween. Jaw member 410 defines achannel or groove 430 therealong that is configured to include a laserfiber 432 that spans along jaw member 410 and is configured to emit alaser light within and along the length of jaw member 410. In someembodiments, the fiber 432 may be substituted by any laser source suchas a fiber laser (e.g., tunable thalium fiber laser) described in thisdisclosure. In further embodiments, the tissue-contacting surfaces 412and 422 may include a transparent coating or cover disposed on thesurface thereof, similar to the tissue-contacting surfaces 112 and 122of FIGS. 2A and 2B.

Jaw member 420 includes a receiving fiber 440 disposed within a cavity444 defined therein that is configured to receive the laser lightemitted from laser fiber 432. In some embodiments, the fiber 440 may besubstituted by any optical detectors described in this disclosure orother suitable optical detectors. An optical window 442 is disposedalong the surface of jaw member 420 between laser fiber 432 andreceiving fiber 440. Optical window 442 may be any suitable type ofoptical lens configured to direct the laser light being emitted fromlaser fiber 432 to receiving fiber 440. Cavity 444 may be configured tocontain a gas or any other medium to facilitate reception of laser lightemitted by laser fiber 432 by receiving fiber 440.

Optical properties of tissue are known to change during heating.Properties such as the absorption coefficient (μ_(a)), scatteringcoefficient (μ_(s)), and anisotropy coefficient (g) have been shown tochange as a function of temperature and time. These properties affectthe transmission and reflection of light as it interacts with tissue.The present disclosure incorporates a receiving fiber 440 that may beused to detect and/or monitor changes in the transmission of laser lightfrom laser fiber 432 through the tissue during a sealing cycle todetermine when a desired tissue effect has been achieved. In thisconfiguration, cut completion, e.g., when the tissue is separated, mayalso be detected and/or monitored using the receiving fiber 440.

FIG. 6 illustrates an embodiment of an end-effector assembly (generallydepicted as end-effector assembly 500) for forming a desiredillumination pattern. End-effector assembly 500 includes jaw members 510and 520 having tissue-contacting surfaces 512 and 522. Similar to theabove-described jaw members, jaw members 510 and 520 cooperate to grasptissue therebetween. Additionally, jaw member 510 defines a channel orgroove 530 therealong that is configured to include a laser cuttingfiber 532 that spans between proximal and distal ends 532 a and 532 b ofjaw member 510. Laser fiber 532 is configured to emit a laser lightwithin and along the length of jaw members 510 and 520. On an opposingside, a receiving fiber 540 is disposed within jaw members 520 andextends along a length thereof and is configured to receive the laserlight emitted from laser fiber 532.

Receiving fiber 540 includes proximal and distal ends 540 a and 540 band also includes one or more sensors 542 therebetween. Sensor(s) 542 isconfigured to monitor a temperature during a seal cycle and providefeedback as to when a seal cycle is complete. Since pressure is a factorin the quality of a seal following a sealing treatment, sensor 542 mayalso determine jaw pressure by measuring the strain in the jaw members510 and 520 resulting from applied mechanical loads when tissue isgrasped between jaw members 510, 520. In this configuration, feedbackmay be provided to an operator (and/or to the controller 42) as towhether the appropriate jaw pressure has been attained prior to energyactivation to achieve a proper tissue seal.

FIGS. 7A and 7B illustrate another embodiment of an end-effectorassembly 600 for forming a desired illumination pattern. End-effectorassembly 600 includes jaw members 610 and 620 having tissue-contactingsurfaces 612 and 622. Similar to the above-described jaw members, jawmembers 610 and 620 cooperate to grasp tissue therebetween. Jaw members610 and 620 each define longitudinal axes “Z-Z” and “Y-Y,” respectively,that span from their respective proximal ends 610 a, 620 b to theirrespective distal ends 610 b, 620 b. Longitudinal axes “Z-Z” and “Y-Y”define an angle “β” that increases as jaw members 610 and 620 areseparated from each other, when pivoted from a closed configuration toan open configuration.

End-effector assembly 600 includes one or more light-emitting elements632 a, 632 b, 632 c, and 632 d that are disposed within a channel 630defined along the length of jaw member 610. Each light-emitting element632 a, 632 b, 632 c, and 632 d is configured to emit a light energywithin and along the length of jaw members 610 and 620. Light-emittingelements 632 a, 632 b, 632 c, and 632 d may be any suitable type oflight-emitting element, for example, but not limited to high-intensityLEDs configured for medical use and/or tissue treatment, optical fibersor other optical elements configured to emit light into the tissue.Light-emitting elements 632 a, 632 b, 632 c, and 632 d may beselectively activatable (e.g., one or a few at a time) and may emitlight at different wavelengths. One or more light-receiving elements 642a, 642 b, 642 c, and 642 d are disposed within a channel 640 definedalong the length of jaw member 620. Each light-receiving element 642 a,642 b, 642 c, and 642 d is configured to detect the light energy emittedfrom the light-emitting elements 632 a, 632 b, 632 c, and 632 d. Thelight-emitting elements 632 a, 632 b, 632 c, and 632 d and thelight-receiving elements 642 a, 642 b, 642 c, and 642 d may be disposedbehind a protective substrate 636 configured to transmit light.

The light-receiving elements 642 a, 642 b, 642 c, and 642 d may be anysuitable light-receiving element, such as a lens, an optical fiber, orphotodetector, and may be configured to measure optical properties ofthe tissue. In some embodiments, the light-receiving elements maycollect and transmit light to optical systems configured to provide avariety of spectroscopic measurements including Raman spectroscopy,which is suitable for determining seal competition and identification ofspecific tissue types and its constituents (e.g., collagen, protein,water, etc.). Raman spectroscopy is described in more detail later inthis description.

In some embodiments the light-receiving element 642 a, 642 b, 642 c, and642 d and the light-emitting elements 632 a, 632 b, 632 c, and 632 d maybe interspersed between the jaw members 610 and 620, such that each ofthe jaw members 610 and 620 includes one or more receiving modules andone or more light-emitting elements. This configuration provides formeasuring optical properties (e.g., reflection and transmission data) ateach jaw member 610 and 620 and allows for use of optical coherencetomography to obtain images of the tissue grasped between the jawmembers 610 and 620. Other techniques for determining optical tissueproperties are disclosed in a commonly-owned U.S. patent applicationSer. No. 12/665,081 entitled “Method and System for Monitoring TissueDuring an Electrosurgical Procedure,” the entire contents of which isincorporated by reference herein.

Each light-emitting element 632 a, 632 b, 632 c, and 632 d may beconfigured to independently adjust its emittance of light energy alongthe jaw member 610 depending on angle “β.” For example, when angle “β”is about 45 degrees (e.g., when jaw members 610 and 620 are movedtowards an open configuration) the distal-most light-emitting element632 d may emit light energy with a greater intensity than theproximal-most light-emitting element 632 a. As angle “β” decreases toabout 2 degrees (e.g., when jaw members 610 and 620 are moved towards aclosed configuration) light-emitting elements 632 a, 632 b, 632 c, 632 dare configured to emit light energy with substantially the sameintensity.

Intensity of the light energy, including individual intensity asdescribed above, transmitted through the light-emitting elements 632 a,632 b, 632 c, and 632 d may be adjusted by the controller 42 based onthe measured angle “β” and/or the gap distance between the jaw members610 and 620. As used herein, the term “gap distance” as used hereindenotes the distance between the tissue-contacting surfaces 612 and 622.Since the jaw members 610 and 620 are pivotable relative to each other,the angle “β” therebetween is directly related to the gap distance andthe two concepts are used interchangeably. Angle “β” may be measuredusing any suitable proximity sensors 633 a, 633 b disposed within thejaw members 610 and 620, respectively. The sensors 633 a, 633 b may becoupled to the controller 42 and include, but are not limited to, HallEffect sensors, RF based sensors, and the like. In some embodiments, thesensors 633 a, 633 b may be a pair of corresponding lighttransmitter/receiver elements. In particular, a sensor may be alight-emitting element (e.g., LED) paired with a photodetector (e.g.,PIN diode).

In some embodiments, the angle “β” may be controlled to achieve adesired gap distance between the jaw members 610 and 620 to match thethickness of the tissue to the optical depth of the light energy. If thethickness of the tissue is not greater than the optical depth of thelight being passed through the tissue, then the light energy is notgoing to be fully absorbed. This occurs if the tissue is compressed suchthat it is thinner than the optical depth of the light energy beingused. In addition, if the tissue is not sufficiently compressed, lightenergy does not fully penetrate the compressed tissue resulting innon-uniform heating of the tissue. Controlling of the gap distance tosubstantially match the optical depth of the light energy with thethickness of the tissue ensures that light energy is optimally absorbed.

In some embodiments where the jaw members 610 and 620 include reflectivesurfaces, such as the jaw members 110 and 120, the angle “β” may also becontrolled while taking into consideration the reflection of the lightfrom the tissue-contacting surfaces 612 and 622.

The controller 42 obtains the angle “β” from the sensors 633 a, 633 band determines the gap distance based on the measurement. The controller42 also obtains the wavelength of the light energy being delivered bythe energy source 40. This may be accomplished by storing a value of thewavelength in memory or any other computer-readable storage device whichmay be either transient (e.g., random access memory) or non-transient(e.g., flash memory). The controller 42 then calculates the desired gapdistance based on the stored wavelength value and stored tissueproperties. The controller 42 also compares the actual gap distanceand/or angle “β” to desired gap distance and/or angle “β” as calculatedbased on the wavelength. Based on the comparison, the controller 42 mayadjust the gap distance and/or angle “β” between the jaw members 610 and620 automatically and/or output the difference for the user. Automaticadjustment may be accomplished by providing the jaw members 610 and 620with automatic closure mechanisms such as those disclosed in commonlyowned U.S. Pat. No. 7,491,202, entitled “Electrosurgical Forceps WithSlow Closure Sealing Plates and Method of Sealing Tissue,” whichdiscloses automatic gap control for electrosurgical forceps, the entirecontents of which is incorporated by reference herein.

For manual gap adjustment, the controller 42 may output the differencebetween actual and desired gap distance and/or angle “β” in anaudio/visual manner. In some embodiments, the actual and desired gapdistance and/or angle “β” or the difference therebetween may berepresented numerically and/or graphically (e.g., color-coded). Thedifference may also be represented by audio alarms (e.g., adjustingfrequency or amplitude of sound pulses).

As discussed in the previous embodiments, light-emitting elements 632 a,632 b, 632 c, and 632 d and receiving modules 642 a, 642 b, 642 c, and642 d may be configured to have optical sensing properties such thateach pair of light-emitting element and receiving module (e.g.,light-emitting element 632 a and receiving module 642 a) may be used tomonitor the sealing process at a particular position. Light-emittingelements 632 a, 632 b, 632 c, and 632 d and receiving modules 642 a, 642b, 642 c, and 642 d may also be configured to monitor the presence andstate of other material in and around the sealing device and may alsomodify a sealing algorithm based upon the information collected.

In other embodiments, light-emitting elements 632 a, 632 b, 632 c, and632 d and receiving modules 642 a, 642 b, 642 c, and 642 d may also beconfigured to inject a heat pulse and measure the response of tissue“T”, measure spectral characteristics in transmission and/or reflection,measure spectral characteristics at different positions, measurespectral characteristics at different light frequencies. Light-emittingelements 632 a, 632 b, 632 c, and 632 d and receiving modules 642 a, 642b, 642 c, and 642 d may also be configured to measure temperature at oneor more locations between proximal and distal ends of jaw members 610and 620.

In FIGS. 8A through 8C, an embodiment of an end-effector assembly 700 isshown for forming a desired illumination pattern. End-effector assembly700 includes jaw members 710 and 720 having tissue-contacting surfaces712 and 722. Similar to the above-described jaw members, jaw members 710and 720 cooperate to grasp tissue therebetween. Jaw members 710, 720 areoperably connected to energy source 40 via an optical fiber 702 thatprovides light energy for treating tissue grasped between jaw members710, 720. The optical fiber 702 may have any suitable shape, forexample, but not limited to, rectangular, oval, and polygonal. Inaddition, distal end 1032 a may also take the form of various suitableconfigurations (e.g., sharp or blunt).

Each jaw member 710, 720 includes one or more channels 730 having one ormore vertically-aligned optical fibers 732 that are configured to emitand receive light energy from energy source 40 via optical fiber 702. Insome embodiments, optical fibers 732 of jaw member 710 arevertically-aligned with optical fibers 742 of jaw member 720 such thatoptical communication is established. That is, one of the optical fibersis a transmitting optical fiber (e.g., optical fiber 732) and theopposing fiber is a receiving optical fiber (e.g., optical fiber 742).Any number of transmitting optical fibers 732 may be disposed about jawmember 710. Additionally or alternatively, any number of transmittingoptical fibers 742 may be disposed about jaw member 720. Thus, in otherembodiments, vertical alignment of optical fibers 732 and 742 is notparticularly necessary.

In some embodiments, end-effector assembly 700 may also include one ormore optical switches 750 that provide selective activation anddetection of light energy to and from jaw members 710 and 720 by anoperator and/or energy source 40. Detection of light energy may beprovided by an optical detector 752 or the like. In some embodiments,each channel 730 may be covered by a transparent cover 736 to allowoptical communication between jaw members 710 and 720. It should benoted that any type of detecting device may be utilized with any of theembodiments presently disclose, for example, but not limited to photodiodes and charged coupled device (CCD) arrays.

FIG. 8B illustrates jaw member 710 having a single channel 730 definedtherethrough that includes a plurality of optical fibers 732, asdescribed above, that are covered by cover 736. Cover 736 may be anysuitable material configured to allow optical communication betweenoptical fibers 732 and 742. In another embodiment, FIG. 8C illustratesjaw member 710 defining a plurality of channels 730 a and 730 btherethrough and also includes a plurality of optical fibers 732 thatare covered by cover 736.

As shown in FIGS. 9A and 9B, in further embodiments, a light dissectionelement 2445 may be disposed on an outer periphery of one of the jawmembers 2110 and 2120. For sake of simplicity only a single jaw member,namely, the jaw member 2110 is discussed herein.

The dissection member 2445 may be a light-diffusing element, such as thelight diffuser 132 described above with respect to FIGS. 2A and 2B. Thedissection member 2445 is coupled via an optical fiber 2446 to thegenerator 40 and is disposed on or along at least a portion of an outerperiphery 2110 a of the jaw member 2110. As it is used herein, the term“outer periphery” denotes any surface of the jaw member 2110, such asthe jaw housing 2116, that is not a tissue sealing contact surface 2112or 2122. The dissection member 2445 may be selectively activated via theswitch 2200 similar to the dissection member 2145 and may incorporatesimilar features, e.g., preventing light energy from being transmittedto the sealing surfaces 2112 and 2122 as described above with respect tothe dissection member 2145.

Referring now to FIG. 10, an embodiment of an end-effector assembly 1900for forming a desired illumination pattern. End-effector assembly 1900includes jaw members 1910 and 1920 having tissue-contacting surfaces1912 and 1922. Similar to the above-described jaw members, jaw members1910 and 1920 cooperate to grasp tissue therebetween. Jaw members 1910,1920 are operably connected via an optical fiber 1911 to a light energysource (e.g., generator 40). In particular, the optical fiber 1911 iscoupled to the jaw member 1910. The light may be provided in differentforms, including, but not limited to lasers, light-emitting diode, andany other suitable type of light energy.

The jaw member 1910 is formed from an optically transmissive materialhaving an outer reflective coating 1910 a. The transmissive material maybe an optically diffusing material, such as, frosted sapphire crystal oran optically scattering material, such as polyoxymethylene, which issold under a trademark DELRIN®, available from DuPont, Willmington, Del.The light from the optical fiber 1911 is transmitted to the jaw member1910 and is contained therein by the reflective coating 1910 a. Thisprevents the light from escaping outside the jaw member 1910 other thanthrough the tissue-contacting surface 1912.

The jaw member 1920 may be formed from any optically absorbent orreflective tissue material. In some embodiments, the jaw member 1920 mayinclude an optically absorbent or reflective coating 1920 a on thetissue-contacting surface 1922. The coating 1920 a and/or the jaw member1920 block the light from passing through the jaw member 1920concentrating the light energy at the tissue grasped between the jawmembers 1910 and 1920.

Light energy is suitable for sealing tissue since it is converted intoheat energy by absorption at a molecular level. In particular, certainmolecules absorb light at certain wavelengths. In addition, as tissue istreated it undergoes physical and chemical changes, thus the wavelengthat which light is optimally absorbed also changes. In some embodiments,light energy may be provided at two or more wavelengths to provide lightenergy that is optimally absorbed by two or more molecules (e.g., tissuetypes).

FIG. 11 shows a light energy surgical system 2600 including the energysource 40 and the forceps 10. The forceps 10 may include any of theembodiments of the jaw members described above. The generator 40 incombination with the forceps 10 may be utilized to generate light havinga desired wavelength. The generator 40 may produce light energy atsingle or multiple wavelengths and may include a plurality of lasersources described above that are capable of producing light at multiplewavelengths. The generator 40 includes a plurality of laser lightsources to generate laser light having a wavelength from about 100 nm toabout 10,000 nm, which covers the majority of the tissue constituents.In particular, the generator 40 includes an ArF excimer laser 2602 a, aKrF excimer laser 2602 b, a XeCl excimer laser 2602 c, an argon-dyelaser 2602 d, an Nd:YAG laser 2602 e, an Ho:YAG laser 2602 f, an Er:YAGlaser 2602 g.

The forceps 10 may be used to determine condition and composition oftissue, as described in further detail above with respect to FIGS. 7Aand 7B. FIG. 12 shows a graph illustrating absorption of various tissueconstituents as a function of the wavelength ranging from ultraviolet(UV) spectrum to infrared (IR) spectrum. Tissue constituents that areencountered in tissue include, but are not limited to water,vasculature, epidermis and other skin layers, whole blood, melanosome,collagen, and the like.

During operation, the forceps 10 is used to analyze tissue, includingmeasuring the absorption thereof. The absorption measurements areanalyzed by the controller 42 of the generator 40 which then determineswhich of the one or more laser light sources 2602 a-2602 g to activateto obtain optimal absorption of the light energy. The controller 42 maybe coupled to a multiplexer (not shown) and/or another optical outputswitching apparatus to control activation of the laser light sources2602 a-2602 g.

The forceps 10 may sense optical tissue properties continuously duringthe sealing procedure and to vary light energy output includingintensity and which of the laser light sources 2602 a-2602 g areactivated. Once it is determined that the sealing procedure is complete,the controller 42 may activate specific laser light sources 2602 a-2602g most suitable for cutting sealed tissue.

Raman-Spectroscopy Method for Analyzing Tissue Fusion Samples In Vitro

Past studies on possible mechanisms for heat-induced tissue fusion,particularly for blood vessel sealing, have utilized mainly eitherdirect microscopic observation or mechanical strength testing. Changeswithin collagen bonds within the fused tissue are thought to be pivotalto the strength of the resulting fusion. It is widely accepted that heatdenatures collagen to a gel-like amalgam, which then forms bonds betweenseparated tissues. However, the actual changes that the collagen withinthe fused tissue undergoes during heat-induced RF tissue fusion and themechanism for the formation of the resulting seal have remained unclear.

The method described herein demonstrated, for the first time, the use ofRaman spectroscopy to characterize fused tissues in RF heat-inducedtissue fusion. It was discovered that tissue restructuring, or morespecifically tissue layer and collagen molecular restructuring in thefusion areas, is a contributing mechanism for a strong tissue fusion.Moreover, it was determined that a decrease in non-reducible collagencrosslinks and an increase in reducible collagen crosslinks occur duringtissue fusion. These changes are associated with collagen undergoingheat treatment and this restructuring provides new insight into theeffects of RF fusion on the biochemical changes in the native collagen.Additionally, the presence of compression pressure during fusionproduced a difference in collagen restructuring. Tissues fused withcompression showed an increase in collagen transformation while tissuesfused without compression showed collagen changes associated with a heattreatment. Overall these insights are the first to demonstrate thepreviously suspected involvement of collagen in RF tissue fusion, bothwith and without concurrent compression, using Raman spectroscopy. Thesemolecular insights help provide information on the transformationoccurring due to RF tissue fusion as well as provide a basis for opticalfeedback methods.

Raman spectroscopy provides an attractive way of rapidly capturing themolecular environment of tissues without destroying or altering thesamples. Raman micro-spectroscopy generates information-rich spectrathat, when combined with chemometrics, provide powerful insight into themolecular diversity within heterogeneous biological samples. Proteinshave been studied using Raman spectroscopy, wherein informationregarding the amino acids (e.g., amide bonds between amino acids andtheir tertiary structure) can be extracted and analysed. Ramanspectroscopy has been used to identify changes within isolated animalcollagen during thermal and chemical denaturing. The method describedherein provides a molecular fingerprint to identify collagen anddemonstrate the powerful ability of Raman spectroscopy to exposespecific molecular changes within collagen. Additionally, it is possibleto deconstruct individual contributors, such as collagen, from anoverall tissue sample for characterization and comparison. By scanningacross an area of interest, individual Raman spectrum at eachacquisition point can be combined to form a Raman map, which is similarto a microscopic image but with the ability to focus on certain chemicalmarkers within the imaged area. The Raman map provides a directobservation of molecular distributions, such as that of collagen fibers,within a sampled area.

The method described herein demonstrates the use of Raman spectroscopyto characterize the RF tissue fusion in vitro. Tissue fusion wasperformed with two tissue types, namely, porcine blood vessels and smallintestines, and the seal quality was accessed based on the mechanicalstrength of the seal given by burst pressure testing, as described laterin this description. The Raman spectra was then acquired for fusionsamples characterized as “strong seal” and “weak seal,” and Ramanmapping was conducted across fusion regions. Raman results werecorrelated to the mechanical strength of the seals, and the differenceon the molecular level was investigated. The Raman maps were comparedwith conventional histopathology microscopic results, and the comparisonresults demonstrated the superiority in characterizing RF tissue fusionand the rich molecular information contained in fused tissue Ramanspectra.

Materials and Methods of the Raman-Spectroscopy Method

Animal Tissue Preparation

Fresh porcine small bowels were obtained from a local abattoir, cut into20-30 cm long segments, moistened with physiological saline andrefrigerated at 4° C. for up to 30 hours (from the time of slaughter)until needed for tissue fusion experiments. Prior to the tissue fusionexperiment, a segment of long samples was selected and immediatelydissected into 5 cm long pieces for tissue fusion experiment. Prepared 5cm samples were kept hydrated in sealed plastic sample bags with salineand used within thirty minutes. Porcine blood vessels were cleaned, cutinto 6 cm long pieces, and then frozen within four hours after theanimal was slaughtered. The frozen tissues were kept at −70° C. Frozenblood vessel samples were only thawed at room temperature immediatelybefore the tissue fusion experiment.

RF Tissue Fusion

RF energy is used as the source for tissue heating. The RF generator wasan energy research tool prototype developed by Covidien, Boulder, Colo.,capable of delivering a programmable sinusoidal current from 0-7 A and apower from 0-350 W. An operating RF frequency of 472 kHz was chosen toavoid neuromuscular stimulation and electrocution. Two tissue sealingdevices were used in the tissue fusion experiment: a commerciallyavailable LigaSure Impact™ instrument (Covidien, Boulder, Colo.) forblood vessel sealing and an anastomosis prototype for small bowelsealing. RF energy control algorithms were loaded to the fusion softwarewritten in LabVIEW (short for Laboratory Virtual Instrument EngineeringWorkbench) (National Instruments Corporation, Austin, Tex.) so that theentire procedure was automated. The algorithm was written to control RFenergy delivery to ensure a continuous heating and a predeterminedimpedance varying profile.

During this tissue fusion experiment, tissue samples were clampedbetween the jaws of the fusion device. RF energy was supplied by the RFgenerator and applied to the tissue samples via electrodes in the jaws.The RF generator also continuously monitored both voltage and currentdelivered to the tissue. The varying tissue impedance was then obtainedby using real-time voltage and current readouts. A compression spring inthe handle of the LigaSure Impact™ device provided a constant pressureof ˜0.3 megapascals (MPa). An air compressor connected to the energyresearch tool prototype supplied a variable compression pressure from 0to 0.5 MPa. Over two-hundred tissue fusions were performed in thistissue fusion experiment.

Temperature Measurement

Tissue temperature was measured using a fine (0.005 inch) tipTeflon-insulated J-type thermocouple (5TC-TT-J-36-36, Omega Engineering,Bridgeport, N.J.). The thermocouple was inserted through slits made onthe sealing device jaws and glued in place at the top of the slit sothat its tip emerged 0.25 mm above the electrode surface. In this waythe thermocouple can be placed in contact with the tissue surfacewithout piercing it, and is insulated from the electrode. Thecommunication between the thermocouple and the computer is achievedthrough a National Instruments (NI) PXI-6289 data acquisition (DAQ)board and an NI SCC-68 terminal block. The latter hosts four NI SCC-TC02Thermocouple Signal Conditioning Modules. Each SCC-TC02 can drive onethermocouple and has individual signal conditioning modules with a 2 Hzlow-pass filter, which filters out the RF signal and eliminates the RFinterference from the thermocouple readout.

Sample Preparation and Imaging

Tissue samples were stored at −80° C., following tissue fusion. Thawedsamples were trimmed and embedded in optimal cutting temperature medium(OCT, Tissue-Tek) by flash freezing in isopentane at −160° C. The OCTblocks were sectioned on a cryostat at −20° C., cutting 15 μm sectionsfor histology and Raman spectroscopy. Sections for histology weremounted on glass, washed with water to remove the OCT, and stained withhaematoxylin and eosin (H&E). Sections for Raman analysis were mountedon MgF₂ slides, stored at 4° C., and imaged without further processing.Visualisation of the H&E-stained sections was performed under 4×magnification on an Olympus IX51 inverted light microscope, captureddigitally and spliced together to allow visualisation of the entirefield.

Raman Microscopy

Tissue Raman maps were collected with a 785 nm laser, using a RenishawInVia spectrometer (Renishaw plc, Gloucestershire, United Kingdom)connected to a Leica microscope (Leica, Wetzlar, Germany) as previouslydescribed. Raman maps were collected over selected regions of interestwith a step size of 75 μm in the x and y direction. At each point aspectrum was collected using 5 accumulations of 5 second scans coveringthe Raman shifts range of 620-1700 cm⁻¹. Samples were tested for nolonger than one hour at room temperature and kept hydrated using saline.

Raman spectra were pre-processed for background removal (baselinesubtraction using weighted least squares) and multiplicative scatteringcorrection. N-FINDR spectral unmixing algorithm was used to determineend-members (pure contributing components of each tissue) and everypixel of the resulting Raman map is represented as a linear combinationof the end-members as previously described and results in an abundancevalue between 0 and 1 for all measured points.

Burst Pressure Measurement

The mechanical strength of the fused tissue was evaluated by a burstpressure (BP) testing system that included a syringe pump, a pressuregauge, a sample injection needle and a surgical clamp to close the smallbowel tissue. The main arm of a Y-splitter tubing system was connectedto a water-filled syringe controlled by the syringe pump. The other twosplit arms were connected to the pressure gauge and the sample injectionneedle, respectively. The surgical clamp sealed the other end of thepiece of fused small bowel. The small bowel tissue was pierced by thesample injection needle to allow water to be infused into the sealedbowel without damaging the seal. High-pressure water inside the fusedtissue caused seal burst at the fusion line. After the initiation of theBP test, the syringe pump drove the water filled syringe at a rate of 20mL/min, which equally increased the pressure in the tubing system aswell as in the fused tissue. When any burst or leak in the fused tissuepocket happened, the pressure gauge spotted a drop in water pressure andthe peak pressure was recorded as the BP.

Results of the Raman-Spectroscopy Analysis

Burst Pressure Test Results

Approximately two-hundred porcine small bowel segments were fused for BPtesting. The BP, as an indication of the fusion mechanical strength,varied significantly with the change of compression pressure duringfusion. Tissue samples fused at compression pressures lower than 0.10MPa displayed an average BP of ˜10 mmHg, while samples fused at highercompression pressures (>0.10 MPa) showed an average BP of more than 20mmHg Increased burst pressures were observed at all compression pressurevalues above 0.10 MPa. The BP results serve as a guideline for the Ramanexperiments carried out in this study. Samples fused at threecompression pressures, at 0, 0.2 and 0.3 MPa, were selected and analysedby Raman spectroscopy in order to understand the resulting differencesin fusion strength.

For blood vessel samples, the LigaSure Impact™ instrument was employed,and the compression pressure was therefore at a fixed value of 0.3 MPa,which was provided by the integrated load spring in the device. Theaverage BP for the blood vessels is above 100 mmHg. The BP differencebetween the blood vessel samples and small bowel samples was mainly dueto tissue differences and the different devices used to perform thetissue fusions.

Raman Results

In FIGS. 14A, 14B and 14C, Raman maps collected over porcine bloodvessel tissue selection are shown. Mapped regions included [A] healthytissue, [B] interface between fused and healthy and [C] fused tissue.White light images of each selected area for Raman mapping are shown insections [A-C] (scale=250 μm) with their corresponding Raman map shownin the red, green and black images. The spectra included in [A-C] showsthe collagen end-member spectrum in red with the intensity of the redcoloring in the Raman maps corresponding to the presence of collagenwithin that pixel. The non-collagen rich tissue end-member spectrum isshown in green and the intensity of the color green in the Raman mapcorresponds to the presence of non-collagen rich tissue within thatpixel.

In FIGS. 15 through 20C, Raman maps collected over porcine bowel tissueselections are shown with no compression (FIGS. 15, 16A, 16B and 16C),compression at 0.2 MPa (FIGS. 17, 18A, 18B and 18C), and compression at0.3 MPa (FIGS. 19, 20A, 20B and 20C). Mapped regions include [A]healthy, [B] interface between fused and healthy, and [C] fused tissue.White light images of each selected area for Raman mapping are shown insections [A-C] (scale=250 μm) with their corresponding Raman map shownin the red, green and black images. The spectra include in [A-C] showsthe collagen end-member spectrum in red with the intensity of the redcoloring in the Raman maps corresponding to the presence of collagenwithin that pixel. The non-collagen rich tissue end-member spectrum isshown in green and the intensity of the color green in the Raman mapcorresponds to the presence of non-collagen rich tissue within thatpixel.

RF fused blood vessels and small bowel samples fused at differentcompression pressures were imaged using Raman spectroscopy. Raman mapswere collected from selected regions within the tissue cross-sectionsincluding fused areas, undisturbed and thus considered ‘healthy’ areas,and the interface between them. Raman maps of selected regions are shownfor a fused porcine blood vessel at 0.3 MPa compression (FIG. 13) andporcine blood vessels (FIGS. 15, 17 and 19). The Raman maps of selectedregions of the porcine blood vessels are shown fused without compression(FIGS. 15A, 17A and 19A), with 0.2 MPa compression (FIGS. 15B, 17B and19B), and with 0.3 MPa compression (FIGS. 15C, 17C and 19C). A whitelight micrograph showing the cross section of each tissue sample isshown in each figure (FIGS. 13, 15, 17 and 19) with rectangular boxeshighlighting the areas that were mapped by Raman. The three areas thatwere selected for mapping included healthy tissue (FIGS. 13A, 15A, 17Aand 19A), the interface between healthy and fused tissues (FIGS. 13B,15B, 17B and 19B), and fused areas (FIGS. 13C, 15C, 17C and 19C). Theresulting Raman map and the end-member spectra identified in the sampleand used to construct the Raman map are shown in FIGS. 13 through 20C.All Raman maps shown were reconstructed from the two end-member as shownin spectra in each panel.

The bottom spectrum (in red) representing the collagen end-memberspectrum within the sample and the top spectrum (in green) representingthe non-collagen rich tissue are shown. The collagen end-member spectrumidentified by the N-FINDR algorithm in each map includes all thecharacteristic features reported in past Raman studies of collagen andcollagen rich tissues. Specifically, Raman bands corresponding to C—Cstretch of proline (855 cm⁻¹), C—C stretch of hydroxyproline (874 cm⁻¹),C—N stretch of proline (919 cm⁻¹), proline (1043 cm⁻¹), and Amide 3(1245-1270 cm⁻¹) are notable. The hydroxyproline and two proline peaksidentified in these spectra are specifically Raman collagen assignmentsconfirming a collagen presence. The end-member spectrum which wasidentified to be non-collagen rich tissue included spectral featuresindicative of biological tissue including bands corresponding tocholesterols (699 cm⁻¹), phenlalanine (1003 cm⁻¹), C—H deformation ofproteins (1262 cm⁻¹) and carbohydrates (1342 cm⁻¹), amide II (1480cm⁻¹), and amide I (1663 cm⁻¹).

FIG. 21 shows mean Raman spectra of healthy and fused tissue areasmapped in porcine blood vessel and bowel tissue. Each spectrum labeled“healthy” represents the mean of all collected spectra from anundisturbed cross section of the tissue. Each spectrum labeled “fused”represents the mean of all collected spectra from the fused crosssection of the tissue. Grey spectra were collected from porcine bloodvessel tissue with and without radio frequency fusion at 0.3 MPacompression as labeled. Spectra shown in black were collected fromporcine bowel tissue with the corresponding compression pressure labeled(in healthy spectrum, the pressure of the adjacent fused tissue isindicated in the label). Raman 940 cm⁻¹, 1443 cm⁻¹ and 1655 cm⁻¹ peaksare highlighted corresponding to the protein alpha helix, CH2 wag, andthe Amide 1 C—N—H stretch respectively.

The mean of all spectra collected from the healthy and fused areas ofthe blood vessel which underwent RF fusion and the bowel tissues whichunderwent RF tissue fusion at 0, 0.2 MPa and 0.3 MPa compressionpressure are shown in FIG. 21. In both the blood vessel and the boweltissues a shift in the peak maximum occurred in the 1663 cm⁻¹ Amide 1band and a change in band shape was observed in the 1443 cm⁻¹ C—Hbending band when comparing the fused mean spectrum from the healthymean spectrum in each sample. Many peaks, including the 940 cm⁻¹ peakrepresenting the protein alpha helix did not appear to change peakposition or shape.

Changes specifically in the collagen rich environments were investigatedthrough a threshold analysis using the end-members identified with theN-FINDR algorithm. Spectra showing an abundance value greater than 0.6of the collagen rich end-member were selected and the mean of thesespectra was then calculated for each map. These means were then comparedbetween healthy and fused areas to identify changes in the collagenenvironment due to fusion via a difference spectrum (FIGS. 22A, 22B and22C). Fused porcine blood vessel tissue showed the changes in the1252-1261 cm⁻¹ peaks and a shift to lower wave-numbers in the 1447 cm⁻¹peak. The 1600-1650 cm⁻¹ Amide 1 band showed a shift to higherwave-numbers. For the bowel tissues, different changes were notedcorresponding to different fusion parameters; however, only the sampleswhich were fused with no compression and at 0.2 MPa compression was usedfor comparison as these sample maps included more than 3 spectra whichmet the threshold requirements. The changes in the collagen rich spectrabetween fused and healthy areas were less pronounced in the porcinebowel tissue samples when compared to fused blood vessels. In comparisonto fused blood vessels, bowel tissue fused at 0.2 MPa compressionpressure demonstrated similar trends in the protein band shifts,specifically in the three broad protein bands, 1245-1270, 1445, and 1665cm⁻¹, corresponding to the Amide 3, CH₂ bending, and Amide 1 bands,respectively, though less distinct. In bowel tissue fused withoutcompression, band shift trends included the 1245 and 1665 cm⁻¹ Amide 3and Amide 1 band, respectively; however, less dramatic shifts were seenin other protein bands (FIGS. 22A, 22B and 22C).

Referring to FIGS. 22A, 22B and 22C, Raman spectra are shown of healthy,RF-fused collagen rich tissue areas from RF fused porcine blood vessel(FIG. 22A), RF-fused porcine bowel tissue without compression (FIG.22B), and at 0.20 MPa compression pressure (FIG. 22C). The 1313 cm⁻¹,1324 cm⁻¹, 1252-1261 cm⁻¹ and 1600-1690 cm⁻¹ peaks are highlightedcorresponding to the CH3CH2 twisting and wagging mode of collagen,respectively; Amide 3 and Amide 1 (nonreducible collagen crosslinks atlower wavenumbers and reducible collagen crosslinks at higherwavenumbers) respectively.

Histopathology Results

FIGS. 23A through 23D show histological sections of fusion samples for:porcine blood vessel (FIG. 23A); porcine small-bowel sample fused at 0MPa (FIG. 23B); porcine small-bowel sample fused at 0.2 MPa (FIG. 23C);and porcine small-bowel sample fused at 0.3 MPa (FIG. 23D).

In FIGS. 23A through 23D, the histopathology results are presented forboth porcine blood vessels and porcine small bowels fused at differentcompression pressures. The porcine small bowel tissue sample fused at nocompression pressure, as shown in FIG. 23B, appears to form a sealbetween the upper and lower small-bowel pieces, where the boundarybetween these two layers can still be seen. The three layers of smallbowel tissue, i.e., serosa, submucosa and mucosa layers, can be clearlyidentified and the delimitations between different layers are apparent.Although the tissue thickness was reduced at the mucosa layer, thetissue structure remains similar to the native tissue. FIGS. 23C and 23Dshow porcine small-bowel samples fused at compression pressures of 0.2and 0.3 MPa. Relative to FIG. 23B, FIG. 23C and FIG. 23D displaysignificant changes in the tissue structure resulting from the appliedcompression pressure. The delimitation between submucosa and mucosalayers is less clear and the thickness of the mucosa layer has reducedconsiderably. Importantly, a more homogeneous amalgam was formed by theupper and the lower mucosa layers in the centre of the fusion region,and the boundary between the upper and the lower mucosa layers hascompletely disappeared.

Tissue Temperature Evolution During Fusion

The embedded thermocouple shows that the tissue temperature evolutionduring fusion has two stages: a rapid increase in tissue temperaturewithin a few seconds followed by a relatively stable plateau where thetissue temperature variation was within the range of ±5° C. The tissuetemperature was determined by the impedance control algorithm. A steeprising slope significantly reduces the duration of the whole procedureand a higher plateau temperature in the range between 60° C. to 90° C.ensures the necessary collagen denaturation in the tissue, which isbelieved to be essential for a strong fusion. It was discovered thatplateau temperatures below 60° C. may not lead to the denaturation ofcollagens, while excessive temperatures need to be avoided as these leadto permanent damage of the tissue or necrosis.

Discussion of the Raman-Spectroscopy Analysis

RF tissue fusion holds promise to reduce some of the complications inexisting bowl anastomosis procedures including post-operative bleedingand leakage. One of the challenges in intestinal tissue anastomosis iseffectively controlling the delivered energy to form a successful fusionwithout causing excessive thermal tissue damage. This requires a betterunderstanding of the heat-induced tissue fusion mechanism and thedevelopment of effective feedback technologies.

This study investigated the use of Raman spectroscopy to providebiomolecular insights into the molecular restructuring which occursduring tissue fusion. Raman results were linked to optimal fusionparameters (compression pressure in particular) obtained by comparing tothe BP testing results and histological sections. Raman spectroscopy wasconducted in order to explain the observed changes in mechanicalstrength shown in the BP measurement of fusions when compressionpressure was changed. Raman spectroscopy was applied to non-invasivelyimage cross sections of healthy and fused tissue as shown in FIGS. 13through 20C. Applying N-FINDR spectral unmixing allowed forvisualisation of the various bowel tissue layers by identification ofthe end-member spectra which are defined by the most extreme spectrapresent within the map. The tissue layers identifiable through Ramanspectroscopy correspond to those layers seen in the white lightmicrographs and in the histological sections by utilizing only twoend-member spectra, one corresponding to a high collagen contributionand the other to non-collagen rich tissue. Raman spectroscopic maps werereconstructed from the two end-members with end-member abundance plotsoverlaid and converted to red green colour images based of thecontribution of each end-member to each collected spectrum. Thesubmucosal layer is clearly distinguished in each small intestinal crosssection by its increased collagen content. During sectioning of theintestinal tissue, the shear force caused some separation of the healthytissue sublayers (serosa, submucosa and mucosa). In FIG. 16A, a loss ofthe serosa is clearly visible in the white light micrograph and thecorresponding Raman map. The collagen rich submucosa is located betweenthe mucosa and serosa. The mucosa and serosa are shown to include manyof the Raman spectral signatures of biological tissues including cells(DNA peaks included) and the extracellular matrix. Collagen Ramansignature bands are found in the mucosa and serosa layers as well;however, these layers appear to be less collagen rich with a greatercellular contribution corresponding to the known constituents of thesetissue layers.

Histopathology results show the fused tissue area to be thinner andlacking the tissue layers visible in healthy tissue. The merging andrestructuring of the biochemical constituents of the tissue layers inthe bowel tissue during RF tissue fusion with compression pressure isonly significantly demonstrated in the Raman maps. At a compressionpressure of 0 MPa, the fused area is visibly thicker, and the tissuelayers are still distinct as shown with the white light images andhistology. The Raman map shows this again with the collagen rich layersremaining very distinct and encased by non-collagen rich layers as seenin FIGS. 17 and 19. As the compression pressure was increased to 0.2 MPathe greatly reduced thickness of the fused area made it hard to visuallydistinguish if the native tissue layers were still preserved post RFfusion. At 0.2 MPa compression pressure the Raman map exposed a collagenrich upper and lower layer in some areas of the fused region and lessdistinguishable collagen layering in other areas (FIG. 17). Further, ata compression pressure of 0.3 MPa there was no distinct layering ofcollagen rich and non-collagen rich regions within the fused tissue andcollagen rich areas are found throughout the thin fused area. Thecollagen within the fused region of samples which underwent compressionalso demonstrated collagen cross linking modification and collagen amidebond modification which were not detected in tissue fused withoutcompression. When comparing these results to the burst pressuremeasurements, it is notable that both the 0.2 MPa and 0.3 MPacompression pressure fused tissues showed median burst pressures of morethan 20 mmHg. The correlation of higher burst pressures in thecompressed fused tissue samples with less distinct tissue layering and amore distinct change in collagen crosslinking supports the hypothesisthat collagen crosslinking modification via RF fusion plays an importantrole in the overall quality of the tissue fusion.

H&E histological stains of the porcine small intestinal tissue showedthat fusion without compression produced a decrease in the tissue crosssectional thickness however the tissue layers and band structuresappeared to remain much like that of the native state and produced amedian burst pressure of less than 10 mmHg RF tissue fusion performedwith accompanying compression showed a dramatic reduction in fusedtissue thickness and significant changes in the tissue layers with thedelimitation between the submucosa and mucosa layers becoming lessdistinguishable as seen in FIGS. 15 through 20C and FIGS. 23A through23D. Additionally, the upper and lower mucosa of the fused tissue becomeindistinguishable from one another in the histological sections, whitelight micrographs and Raman maps. Fusion is therefore demonstrated bythe unification of the mucosa during fusion along with the increase inburst pressure.

This method compares the collagen rich spectra from healthy and fusedtissue. In order to perform this analysis the collagen rich spectra wereidentified by those having an abundance value greater than 0.6 for thecollagen end-member spectrum found in each Raman map. The mean of allspectra which were identified to be predominantly collagen was thencalculated and the healthy and fused tissue collagen was comparedthrough the difference spectra of these collagen means as shown in FIGS.22A through 22C. This analysis was performed on both fused porcine bloodvessels as well as fused porcine bowel tissue. The difference spectrumcomparing areas of fusion to healthy tissue in blood vessels showedsimilar band shifts and thus biomolecular bond changes in twoindependent samples. These trends included the denaturing of collagenshown through the shift of the 1660 cm⁻¹ band to higher wave-numbers inthe fused tissue area, also suggesting an increase in reduciblecrosslinks and a decrease of non-reducible cross links within thecollagen. Additionally, a shift in the 1302 cm⁻¹ peak to higherwave-numbers has been previously reported in collagen thermaldenaturing. Changes in the 1313 cm⁻¹ and 1324 cm⁻¹ peaks signifyingchanges in the CH₃CH₂ twisting and wagging modes of collagen alsodemonstrated a disruption to the native collagen. Lastly, the apparentshift of the 1252-1261 cm⁻¹ peaks to lower frequencies also implicatecrosslinks may have been reduced or broken. RF fusion of the porcinebowel tissue demonstrated less pronounced differences; however, fusionperformed at 0.2 MPa compression pressure demonstrated many of the samechanges, including shifts in the 1252-1261, 1313, 1324, 1443, and 1660cm⁻¹ bands, seen in the fused blood vessels, again indicating adenaturing of collagen and, more specifically, a decrease innon-reducible cross links and an increase in reducible cross links asseen in FIG. 23C.

Tissue fused without compression appears to undergo some molecularrestructuring as indicated in the mean plots (FIG. 21) which may beexpected due to exposure to higher temperatures. This molecularrestructuring appears to be less collagen dependant as shown in theRaman difference plots in FIG. 22B with collagen difference spectrumhighlighting fewer distinct band shifts in compressed tissue versusnon-compressed tissue. This may be attributed to more collagen bondrestructuring with the additional mechanical pressure during fusionintroduced with tissue compression.

Particular consideration to Raman spectral background changes was takenduring the analysis of the Raman tissue maps as fiber and water contentmay alter the Raman background signal. A polynomial fit was used toremove the background and spectra were normalised before comparing meansdirectly or through difference spectra. Changes within the Ramanspectral backgrounds were in line with expectations with the fusedregions being more dense, less hydrated and less organized into distincttissue layers. Some of the difference spectra were not considered (i.e.,0.3 MPa compression pressure) as those tissue areas showed less than 3spectra with an abundance value greater than 0.6 for the collagen richend-members. When comparing difference spectrum it is also important tonote collected Raman spectra are semi-quantitative thus general trends(peak shifts and shape changes) are more comparable than absoluteintensity differences. It is contemplated that smaller mapping stepsizes and/or a larger tissue section may be considered to improve uponthese challenges.

As shown herein, the correlation between the Raman maps and thehistological maps supports the utilization of Raman spectroscopy in theinvestigation of RF tissue fusion quality and tissue restructuring. Thepresently-disclosed method of Raman spectroscopy allowed for highlyspatially resolved mapping that provided biochemical information withoutsuffering from hydration and tissue density changes between the healthyand fused tissue. The information rich nature of the collected Ramanspectra combined with multivariate statistical analysis allowed theselection and comparison of the collagen content between tissue sectionsof interest. These abilities may be utilized when investigations of RFtissue fusion and comparable techniques are compared in situ and invivo. Raman microscopy has been demonstrated to be translatable into theclinical setting. Thus the rapid, non-destructive, hydration anddehydration-compatible technique utilized in this study holds promise tofurther elicit information in the translation of the technique to bowelanastomoses.

Laser-Induced Tissue Fluorescence in Monitoring RF Tissue Fusion Method

The use of heat for tissue sealing or approximation has attracted muchattention in many surgical fields. For example, heat-induced vesselsealing by energy-based devices has been experimentally studied andclinically implemented for some time. Different energy sources have beenused for tissue heating and fusion, including ultrasound, RF, and laserenergy. Of these, ultrasonic dissectors (e.g., Cusa, Cavitron UltrasonicSurgical Aspirator, Covidien, USA; Selector, Surgical Technical Group,Hampshire, GB; Autosonix Autosuture, Norwalk, Conn., USA; Ultracision,Ethicon Endo-Surgery, Norderstedt, Germany) and RF bipolar vesselsealers (e.g., LigaSure Impact™, Covidien, Boulder, Colo.) arecommercially available and clinically used as common practice in theoperating theater.

The method described herein presents a novel tissue fusion monitoringand characterization technology using laser-induced fluorescencespectroscopy, which provides further insight into tissue constituentvariations at the molecular level. In particular, an increase offluorescence intensity in 450-550 nm range for 375 and 405 nm excitationsuggests that the collagen cross-linking in fused tissues increased.Experimental and statistical analyses showed that, by using fluorescencespectral data, good fusion could be differentiated from other cases withan accuracy of more than 95%. This suggests that fluorescencespectroscopy can be used as an effective feedback control method inreal-time tissue fusion.

Bowel anastomosis is a routine procedure in modern surgery to restorebowel continuity after surgical resection due to intestinal malignancy,inflammation or obstruction. It has been estimated that 2.5 millionbowel anastomoses are performed annually worldwide. The existing tissueanastomosis techniques of suturing and stapling may have limitations andproblems such as bleeding and leakage from suturing sites. Thesecomplications may result in trauma, infection, and retained foreignmaterials, leading to a significant increase in morbidity, mortality andadditional cost in treatment. Energy-based anastomosis devices hold thepromise of replacing hand-suturing and stapling in surgery to become thenext generation anastomosis technology. Such a technology exploits theheat-induced anastomosis of native tissues. High-quality tissue sealingas a result of simultaneously applied heat and compression pressure canbe achieved without using any foreign materials, and thus, is expectedto greatly reduce morbidity, mortality and additional treatment cost.

There are two main challenges that need to be addressed in this field.Firstly, although the mechanism for heat-induced tissue fusion,particularly for blood vessel sealing, has been studied, such a processis not fully understood on a molecular level. Secondly, existingthermotherapy procedures mainly rely on predetermined dosimetry such asheating power or applied voltage. In bowel anastomosis, however, due tothe complex and variable nature of bowel tissue, instead ofpredetermined dosimetry, a monitoring or feedback control strategyshould be implemented in real time. Parameters including temperature,thermal spread, optical transmittance and impedance have been suggested,but it has been unclear how these parameters may provide insights intomolecular structural changes.

The presently-disclosed method uses laser-induced fluorescence fromendogenous fluorophores to noninvasively characterize tissue. Variationin laser-induced fluorescence properties is often due to changes influorophore concentration, fluorophore spatial distribution, metabolicstate, biochemical/biophysical microenvironment, tissue architecture,and attenuation arising from chromophores and scatterers. The endogenousfluorophores in tissues consist of collagen crosslinks (excitation: 360nm; maximum emission: 450 nm), elastin (325 nm; 400 nm), NAD(P)H (351nm, 460 nm), FAD (450 nm; 535 nm), bile (380 nm; 425 nm) andlipopigments (broad excitation and emission). The laser-inducedfluorescence spectrum mainly arises from the superposition of thefluorescence from all of these fluorophores.

Intestinal tissues share many compositional similarities with othertissue types, including the fluorophore content such as collagen andelastin. The gastrointestinal tract consists of four distinct layers(mucosa, submucosa, muscularis, serosa) that possess differentfluorescence characteristics due to variations in fluorophorecomposition and arrangement. The submuscosa is by far the mostfluorescent layer for ultraviolet (UV) excitation due to its highcollagen content, and this can be used as the basis of characterizationof intestinal tissues subject to heat using laser-induced fluorescence.This method involves the fluorescence emission from collagen crosslinks,which are an important indicator for tissue fusion mechanical strength.Further, the methods of fluorescence spectroscopy may be fast,noninvasive and quantitative. Considering that only a few points need beprobed and that certain discrete spectral features can be used to createa diagnostic indicator, the presently-disclosed fluorescencespectroscopy method may be a relatively inexpensive and accessiblemodality to implement and use.

In accordance with the method described herein, heat-induced porcinesmall-bowel fusion was performed by using RF energy and demonstrates theuse of laser-induced fluorescence to characterize fusion in vitro.Histopathology analysis was conducted to gain direct knowledge into thefused-tissue architectural changes. Fused-tissue mechanical strength wasassessed by a burst pressure (BP) testing system. The tissuefluorescence spectra was measured with two excitation lasers at 375 and405 nm, and the difference in the fluorescence spectra in relation tothe quality of fusion was investigated. Using laser-induced fluorescenceto determine the fusion quality is also discussed.

Materials and Methods of the Laser-Induced Tissue Fluorescence inMonitoring RF Tissue Fusion Method

Animal Tissue Preparation

Fresh porcine small bowels were obtained from a local abattoir, cut into20-30 cm long segments, moistened with physiological saline andrefrigerated at 4° C. for up to 30 hours (from the time of slaughter)until needed for fusion experiments. Prior to the fusion experiment, asegment of small bowel was selected and immediately dissected into 5cm-long pieces for tissue fusion experiment. Prepared 5 cm samples werekept hydrated in sealed plastic sample bags with saline and used within30 minutes.

RF Tissue Fusion

RF energy is used as the source for tissue heating. The RF generator isan energy research tool prototype (developed by Covidien, Boulder,Colo.) capable of delivering a programmable sinusoidal current from 0-7A and a power from 0-350 W. An operating RF frequency of 472 kHz waschosen to avoid neuromuscular stimulation and electrocution. A bipolaranastomosis prototype was used as the tissue sealing device in thisexperiment with jaws to clamp on the tissue sample, with RF energysupplied by the embedded electrodes in the jaws during the applicationof compression pressure provided by an air compressor connected to thejaws. Pre-written RF energy control algorithms were loaded into thetissue fusion software written in LabVIEW (National InstrumentsCorporation, Austin, Tex.) in the PC to control the entire procedure.The algorithm was configured to control RF energy delivery to ensure apredetermined variation in tissue impedance profile, that is, to firstlyraise the tissue impedance rapidly to a starting threshold, and then tomaintain a slowly rising impedance until the impedance finally reachesthe pre-set end-impedance

During RF fusion, a piece of porcine small-bowel sample was clampedbetween the fusion device jaws. The RF generator supplied the RF energyand also continuously monitored both the voltage and the currentdelivered to the tissue. The varying tissue impedance was then obtainedby using the real-time voltage and current readouts. The air compressorwas capable of supplying a variable compression pressure from 0-0.5 MPavia a pneumatic system integrated with the anastomosis prototype device.

Temperature Measurement

Tissue temperature was measured using a fine (0.005 inch) tipTeflon-insulated J-type thermocouple (5TC-TT-J-36-36, Omega Engineering,Bridgeport, N.J.). The thermocouple was inserted through slits made onthe sealing device jaws and glued in place at the top of the slit sothat its tip emerged 0.25 mm above the electrode surface. In this waythe thermocouple was in contact with the tissue surface without piercingit, and was insulated from the electrodes. The communication between thethermocouple and the computer was achieved through a NationalInstruments (NI) PXI-6289 DAQ board and an NI SCC-68 terminal block. Thelatter hosted four NI SCC-TC02 Thermocouple Signal Conditioning Modules.Each SCC-TC02 could drive one thermocouple and had individual signalconditioning modules with a 2 Hz low-pass filter, which filtered out theRF signal and eliminated the RF interference from the thermocouplereadout.

Laser-Induced Tissue Fluorescence Measurement

The UV laser fluorescence system employed two excitation laser diodesemitting at 375 nm and 405 nm. These excitation wavelengths wereselected in order to determine the endogenous fluorescence properties ofvarious tissue samples. A custom made fiber-optic probe (Romack, Inc.,Williamsburg, Va.) formed a two-way laser delivery and fluorescencecollection device, consisting of six hexagonally packed collectionfibers surrounding an excitation fiber. The diameter and numericalaperture of the fibers were 200 μm and 0.22 respectively and the fibermaterial was chosen to have low autofluorescence and attenuation in theUV spectral region of interest. The probe distal tip was covered by aglass window and the fibers and window were housed in a stainless steeltube with an external diameter of 2 mm. This configuration enabled it tobe inserted into small slits made on the sealing device jaws forreal-time analysis. The proximal end was divided into two arms, thefirst arm contained the excitation fiber and was coupled to the laseroptics using an SMA connector; the second arm included the six emissionfibers arranged in a linear array inside another SMA connector. Duringlaser-induced fluorescence, the proximal end was made perpendicular tothe sample plane, in gentle contact with the sample without inducing anypressure.

The laser outputs were collimated by 4.6 mm focal length lenses and thebeams were coupled into the excitation fiber using an 8 mm achromaticfocusing lens. Two steering mirrors were used to optimize the alignmentand maximize the coupling efficiency. Two program-controlled beamshutters were placed in front of laser diodes to switch laser exposureon and off as well as to control the exposure durations. The outputoptical power at the distal end of the probe was 3.5 mW.

The fluorescence emission from the six collection fibers was focussedonto the 80 μm wide input slit of an imaging spectrograph (SpectralImaging Ltd., Oulu, Finland) using an achromatic lens doublet (60 mm and30 mm). A 430 nm long-pass filter was inserted between these two lensesto block the excitation laser reflections from the sample. The lightdispersed by the prism-grating-prism element of the spectrograph wasthen acquired with a sensitive cooled CCD camera (e.g., Retiga EXI,Qlmaging, Surrey, Canada, 1392×1040 pixels). All the optical componentswere assembled together using a cage system and a breadboard so that thesystem was robust and portable. A LabVIEW program controlled theexposure time and beam shutters and enabled acquisition of fluorescentsignals from the laser diode with an adjustable number of measurements.

Burst Pressure Measurement

The mechanical strength of the fused tissue was evaluated by a BPtesting system that included a syringe pump, a pressure gauge, a sampleinjection needle and a surgical clamp to close the small bowel tissue.The main arm of a Y-splitter tubing system was connected to awater-filled syringe controlled by the syringe pump. The other two splitarms were connected to the pressure gauge and the sample injectionneedle, respectively. The surgical clamp sealed the other end of thepiece of fused small bowel to make it a “tissue balloon.” The sampleinjection needle was used to pierce the small bowel tissue to allowwater to be infused into the sealed bowel without damaging the seal. Asthe amount of water inside the tissue was increased at a rate of 20mL/min using the syringe pump, the pressure also increased until thefused tissue leaked or burst at the fusion line, and the highest valueof water pressure recorded by the pressure gauge was the BP.

Histopathology Analysis

To assess how the structural changes influence the tissue qualitatively,histological examination of RF-fused tissue was carried out. Samples ofporcine small bowel were fused and histological sections were takenbefore and after fusion. The samples were dissected and conserved informaldehyde, stained with haematoxylin and eosin (HE), slicedtransversal to the seal, and were prepared on microscope slides.

Results of the Laser-Induced Tissue Fluorescence Analysis

Tissue Temperature Evolution During Fusion

The tissue temperature variation was a result of the variation in RFenergy supplied to the tissue as determined by the specific impedancecontrol algorithm used. The embedded thermocouple showed that the tissuetemperature evolution during fusion had two stages: firstly tissuetemperature rose rapidly from the initial tissue temperature to a highervalue usually within a few seconds and then the tissue temperaturebecame relatively stable, where the tissue temperature variation waswithin the range of 60° C. to 90° C. Such temperatures ensure thenecessary collagen denaturisation and are believed to be essential for astrong fusion. Temperatures that are too low (<60° C.) may not causedenaturisation of collagen, and temperatures that are too high should beavoided in practice because it may lead to permanent damage on thetissue or necrosis.

Tissue Fusion and Burst Pressure Tests

Tissue samples from the same animal were used in the fusion experiment.Fusions were carried out by controlling the RF energy in order toachieve a predetermined tissue impedance variation with a rising slopeof 0.01 Ω/ms to an end impedance of 200Ω. Fifteen samples were fusedwith five at each of the following compression pressures: 0.05, 0.15,0.25 MPa. Prior to fluorescence spectroscopy, the fusion strength ofthese samples was tested using the BP measurement device and resultsappear in FIG. 24. Fusions made at higher compression pressures (0.15and 0.25 MPa) had a higher mean BP of ˜40 mmHg Samples fused at 0.05 MPaof compression pressure displayed an average BP of less than 10 mmHg.The histopathology and fluorescence spectroscopy results from thesesamples are given in the following sections to understand the differencein the fusion strength.

Histology

Histological images for fused samples are shown in FIGS. 25A and 25B. At0.05 MPa, some degree of thermal damage, as well as tissue compression,can be seen. Residual muscle can still be identified, and cleardemarcation among tissue layers can be observed. A higher compressionpressure at 0.15 MPa resulted in a much thinner and homogeneous fusedregion, with the disappearance of structural features. Serosal andmuscle layers were highly compressed, the submucosa and mucosa weremerged into one homogenous layer, and a higher thermal damage could beseen. The observable features of fusions at 0.25 MPa compressionpressure is similar to that of 0.15 MPa fusions, although some degree ofcracking can also be seen, which might be due to the formation of steamvacuoles during RF fusion. Samples fused at 0.05 MPa of compressionpressure were clearly under-fused. Samples fused at 0.15 and 0.25 MPa ofcompression pressure displayed similar architecture and features, beingcloser to a well-fused state. These histology results are consistent andreproducible among samples fused with equal fusion parameters.

Fluorescence Spectroscopy

In total, 804 fluorescence spectrum acquisitions were made on thefifteen fused tissue samples, with half made at each excitationwavelength (375 nm and 405 nm). Of these, 240 were “control”acquisitions on unfused tissue, 192 were “poorly fused” acquisitions at0.05 MPa compression pressure, and 372 were “well-fused” acquisitions at0.15 and 0.25 MPa compression pressures. FIGS. 26A through 26D show themean fluorescence spectra and associated standard deviation error bars.For each excitation wavelength, both normalised (arbitrary units) andnon-normalised (counts) spectra were displayed in order to show changesincurred to both waveform and overall intensity of the spectra.

The 375 nm laser excited mean fluorescence spectra displayed a mainemission peak close to 455 nm, a slight shoulder around 500-515 nm, asecondary peak around 590 nm, and a narrow peak at 680 nm. The 405 nmlaser excitation spectra showed a main peak in the 470-500 nm region,and a secondary peak around 590 nm. In the normalised spectra, thesteepness of the 375 nm excitation spectra seemed to increase in the460-550 nm region from the “control” to “poorly fused” and then to“well-fused” samples. In the control cases a shoulder was visible around500-510 nm, which became less apparent for the increased fusion cases.For the normalized 405 nm excitation spectra, a slight blue-shiftingseemed to occur around 475 nm, and this primary peak had greaterintensity. In the non-normalised spectra, overall intensity appeared toincrease with fusion, for both the 375 nm and 405 nm excited spectra inthe 440-470 nm and 470-490 nm bands respectively. Additionally, not onlydid the average intensity increase with improved fusion, but there wasalso a greater variability in the magnitude of this intensity among theacquired spectra.

Data Analysis

Kruskal-Wallis non-parametric testing was applied to the fluorescencespectra and based on the features of the mean fluorescence spectra twospectral parameters were chosen: i) the ratio of normalized fluorescenceemission intensity at two distinct wavelengths: I_(n)(520 nm)/I_(n)(490nm) for 375 nm excitation, and I_(n)(575 nm)/I_(n)(475 nm) for 405 nmexcitation; ii) the average normalised intensity between 440 nm to 470nm for 375 nm excitation, and between 470 nm to 490 nm for 405 nmexcitation, symbolized as I_(t)(440-470 nm)_(av) and I_(t)(470-490nm)_(av), respectively. FIGS. 27A through 27D show the associatedboxplots for Kurskal-Wallis testing results. With the significant levelα=0.05, P-values obtained shows the means for these two parameters aresignificantly different among the different classes.

Sparse Multinomial Logistic Regression (SMLR) was applied to thespectral dataset, with the purpose of, resorting to the most relevantspectral features, enabling classification of data into three classes:control, poorly fused and well fused. Over four-hundred input sampleswere used, where each sample consisted of a concatenation of thenormalised 375 nm and 405 nm excited spectra of a given acquisition,associated to its appropriate quality of fusion label. The fluorescenceemission values in the 335 nm and 650 nm range were used as features inthe SMLR test. To assess SMLR classification, a K-fold cross-validationstrategy was adopted, where each subset contained the sixnon-independent acquisitions made during each probing, yielding K=67.

The general accuracy in classifying the test data was 94.3%. Forwell-fused tissue (as defined by burst pressure testing), it could bedifferentiated from poorly fused and control tissue via SMLR with 95.2%sensitivity, 95.4% specificity, 94.7% positive predictive value (PPV)and 95.8% negative predictive value (NPV). Poorly fused tissue could bedistinguished from other tissue states with 89.5% sensitivity, 97.1%specificity, 90.5% PPV and 96.7% NPV. Control tissue could bedistinguished from any fused state with 100% sensitivity, 100%specificity, 100% PPV and 100% NPV.

Discussion of Laser-Induced Tissue Fluorescence Analysis

The histological results in FIGS. 25A and 25B show that highercompression pressure during fusion led to significant changes to thetissue structures, with a homogeneous amalgam formed along the fusionline and the boundary between the upper and lower mucosa layerscompletely removed. The BP tests also confirmed that fusions where anamalgam was formed are stronger. The formation of the amalgam can beunderstood as a result of the combination of compression pressure andheating. When RF energy was applied to the tissue sample, the biologicalimpedance of the tissue converted energy into heat, which led to anincrease in the local tissue temperature. At temperatures higher than60° C., collagen fibers start to be denatured, whereby the chains ofcollagen became untied and formed more cross-links amongst each other.The application of compression pressure compressed the elastin and, as aresult, reduced the space between collagen fibers, which may haveenabled and accelerated the formation of collagen cross-links.Therefore, it seems that the amalgam along the fusion line consists ofincreased collagen crosslinking, which consequently leads to strongfusions. The laser-induced tissue fluorescence spectra were believed tocontain the additional information on collagen crosslinking, which areunavailable with existing tissue fusion characterization modalities.

From the bowel spectroscopic measurements described herein, spectralresults seem to be consistent with existing large bowel ex vivo studiesat both 375 and 405 nm. The main peak can be explained as collagen typeI, NADH, FAD, and by additional bile and cholesterol contributions.Specifically, the 375 nm excited shoulder in the 500 nm region can beattributed to FAD and the 590 nm secondary peak might be related tolipopigments, or to increased haemoglobin absorption in the 540-580 nmregion. The variable appearance of a peak at 680 nm for some of theacquisitions is thought to be correlated to the fluid bowel contentsstill existent in the luminal area of some samples. Bowel contents arerich in lipids, lipopigments (e.g., lipofuscin) and bile acids, all ofwhich emit fluorescence above 600 nm for our excitation wavelengths.This would also explain why the 680 nm peak appears more often forcontrol (FIGS. 26A through 26D), since in fused samples the fluidcontents would have been expelled sideways.

Some previous studies coupling thermo-transformations to tissuefluorescence noticed decreases in intensity, whereas results inaccordance with the presently-disclosed method show increases inintensity in the 440-500 nm range. This contradiction is understandablebecause the previous works studied the sole effect of laser damage onthe tissue, or tissue necrosis, which is different than the process inRF fusion that aims to seal the tissue as opposed to causing damage.Changes in NADH and FAD fluorescence probably arise due to the fact thatthermal damage leads to the destruction of cellular organelles, namelymitochondria, which might, in turn, alter NADH and FAD metabolic statesor even destroy the molecules as a whole.

Increase in fluorescence emission intensity, especially in the 440-500nm range, may arise from both collagen crosslinking and tissuearchitectural changes. On one hand, the RF energy-induced heating oftissue leads to the breaking of existing collagen bonds, and then newcollagen crosslinks form as a result of applied RF energy andcompression. On the other hand, the significant increases influorescence intensity are considered to be related to the generaltissue architectural changes due to the joint action of RF energy andpressure. Firstly, as seen in the H&E sections, the thickness ofwell-fused bowel ranges from 25 micrometers (μm) to 50 μm, as opposed tonative bowel that might have a two-walled thickness on the order ofmillimeters. Since the laser light penetration depth is only a fewhundred micrometers, for fused samples excitation and fluorescencecollection is possible throughout the entire sample depth. Secondly, thefact that bowel layers are compressed means that there is a higherconcentration of fluorophores per unit volume in fused samples comparedto normal tissues. A third factor is the compaction, which means thatthe probe is in closer contact with the most fluorescent layer, thesubmucosa.

The method described herein demonstrated for the first time the use oflaser-induced fluorescence to characterize the fused tissues inheat-induced tissue fusion. The fluorescence results were correlated toboth BP and histological results to provide further insights into themechanism for heat-induced tissue fusion. The fluorescence spectra andstatistical analysis show clearly that different tissue fusion classeshave distinct fluorescence spectral features. This paves the way forusing laser-induced fluorescence as an advanced feedback control methodto understand as well as to control the tissue fusion. The existingparameters in tissue-fusion feedback control are mainly tissuetemperature and tissue impedance. Unfortunately, these two parameters donot provide the most reliable indication of the quality of the tissueseal. Methods and systems for monitoring of tissue during a surgicalprocedure in accordance with the present disclosure utilize fluorescenceas a parameter, wherein the formation of the collagen cross-link basedamalgam can be directly monitored, which further reveals the fusionstrength.

Real-Time RF Energy-Induced Tissue Seal Fluorescence Monitoring Systemand Method

In FIG. 28, a system for treating tissue (generally referred to hereinas system 2800) is shown and generally includes a RF generator 2840 anda surgical instrument 2810 with an end-effector assembly 2811. Surgicalinstrument 2810 may be any device or instrument suitable for tissuefusion, e.g., a LigaSure Impact™ instrument (Covidien, Boulder, Colo.).Surgical instrument 2810 is connected through a transmission line 2815(e.g., a bipolar cable) to the RF generator 2840. Surgical instrument2810 may be configured to be connectable to one or more energy sources,e.g., laser sources, RF generators, and/or self-contained power sources.Surgical instrument 2810 and the end-effector assembly 2811 are similarto the surgical instrument 10 and the end-effector assembly 100 shown inFIG. 1A, and further description of the like elements is omitted in theinterests of brevity.

System 2800 is configured for fluorescence real-time monitoring andincludes a computer 2830, a spectrometer 2850, a generally Y-shaped twoway fiber-optic probe 2820 having one end coupled to the end-effectorassembly 2811 of the instrument 2810, a laser source 2860 (also referredto herein as excitation source 2860), and a beam splitter 2867 withmirror 2869, which channels the light from different light sources intoa single optical fiber. In some embodiments, as shown for example inFIG. 28, the Y-shaped fiber-optic probe is a custom-made fiber-opticprobe (LEONI Fiber Optics GmbH, Muehldamm, Germany). This set-up resultsin the formation of a two-way laser delivery and fluorescence collectiondevice. System 2800 may include additional, fewer, or differentcomponents than shown in FIG. 28, depending upon a particular purpose orto achieve a desired result.

Fiber-optic probe 2820 is configured be inserted into an aperture formedin one of the jaw members of the end-effector assembly 2811. Theaperture (not explicitly shown) is configured to be small enough toavoid interference with mechanical strength and electrical parameters ofthe surgical instrument 2810. The proximal end of the fiber-optic probe2820 is divided into two arms. The first arm is configured to containone or more excitation fibers (e.g., excitation fiber 3172 shown in FIG.31) coupled to the optical output of the laser source 2860. The secondarm of the fiber-optic probe 2820 includes one or more emission fibers(e.g., emission fiber 3172 shown in FIG. 31) connected to a registrationdevice, e.g., spectrometer, photodiode, CCD/CMOS camera, etc. Theexcitation source may include any number of light sources, e.g., laser,LEDs or lamps with bandpass filters, with an appropriate wavelength andpower. In some embodiments, as shown for example in FIG. 28, theexcitation source 2860 includes two diode lasers with emissionwavelengths of 375 nm (L375P020MLD, Thorlabs Inc., Newton, N.J.) and 405nm (Thorlabs' DL5146-101S), respectively. To choose an appropriateexcitation wavelength the mechanical beam shutters (e.g., two shutters2861 and 2862), optical switchers or light source power commutation maybe used.

In some embodiments, the spectrometer 2850 may be a high-sensitivitycompact spectrometer, e.g., an Ocean Optics USB4000-FL (Ocean OpticsInc., Dunedin, Fla.), used for fluorescence spectra registration.Spectrometer 2850 may have a longpass filter (e.g., Thorlabs' FEL0450)with a cut-off wavelength of 450 nm for rejection of excitation laserlight in the optical entrance.

Shutters 2861 and 2862 may be any suitable optical beam shutters. Forexample, shutters 2861 and 2862 may be optical beam shutters thatutilize a rotary, electro-mechanical actuator to provide millisecondshutter operation (e.g., Thorlabs' SH05 Beam Shutter), and may beconfigured to open when a pulse control signal is applied.

Computer 2830 may include one or more central processing units (CPUs),which may be coupled to a memory (not explicitly shown). CPUs mayinclude any type of computing device, computational circuit, or any typeof processor or processing circuit capable of executing a series ofinstructions that are stored in a memory. CPUs may be adapted to run anoperating system platform and application programs. In some embodiments,the computer 2830 may include a plurality of computer nodesinterconnected by a network, e.g., the Ethernet or other computernetworking technologies. In some embodiments, the computer 2830 isconfigured to run LabVIEW software (National Instruments Corporation,Austin, Tex.) used for managing the spectrometer 2850 and the excitationsource 2860, synchronization with the RF generator 2840, spectravisualization, preliminary data treatment and/or storing.

During operation of the system 2800, the temporal profile of tissuefluorescence features provide real-time information about thebiochemical and structural state of tissue fusion, which cannot bedetermined using other modalities such as histology or infraredthermography. Tissue fluorescence can be monitored, using the system2800, during RF tissue fusion and after RF application, when monitoringof electrical parameters and temperature is not possible or is no longerinformative to the surgeon. During operation of the system 2800, it ispossible to register fluorescence spectra exactly at the moment at whichRF application begins and is switched off. During operation of thesystem 2800, fluorescence data can be used for optimization of the RFdelivery protocol, thereby avoiding excessive tissue thermal damage orincomplete fusions, both states which would be incompatible for in vivotissue healing and survival.

When the operator pushes the “Start” button on sealing device 2810, theRF energy generator 2840 commences electrical energy delivery. From thedata output point of the RF generator a “HIGH” signal is seen. Thisoutput is connected to an analog-to-digital converter (ADC), e.g., NIDAQ USB-6009 (National Instruments Corporation, Austin, Tex.) which iscompatible with LabVIEW. Although not explicitly shown in FIG. 28, theADC is represented by an electronic connection between the RF generator2840 and the computer 2830. The signal from the ADC is interpreted by aLABVIEW program and fluorescence acquisition begins immediately.Excitation light with wavelength 375 nm or 405 nm, embodied in lightsource 2860, is chosen by appropriate opening/closing of the beamshutters 2861 and 2862. When shutter 2861 is open, shutter 2862 isclosed and only the 375 nm excitation light is delivered to the tissue,while the spectrometer 2850 acquires the fluorescence spectrum of thetissue excited at 375 nm wavelength in range 450-1000 nm. Followingspectral acquisition, shutter 2861 is closed and shutter 2862 opens. Thespectrometer 2850 acquires the fluorescence spectrum of tissue excitedat 405 nm in the same range. In some embodiments, this cycle is repeatedevery 300 ms. When RF energy delivery is switched off, the signal fromthe RF generator servicing output is switched to “LOW.” The signal fromthe ADC is interpreted by the LABVIEW program as being the terminatingpoint of RF fusion. Fluorescence spectra acquisition can then beterminated or continued for as long as necessary according to the setprotocol (e.g., 6 seconds). In some embodiments, at the end ofacquisition, the fluorescence spectra are saved in separate files foreach excitation wavelength. For each spectral acquisition, informationis collected about time from the beginning of fusion and when RF energywas applied in relation to commencing spectral acquisition.

In FIG. 31, an embodiment of the system 2800 in accordance with thepresent disclosure (referred to herein as the “real-timemulti-wavelength laser-induced fluorescence spectroscopy system 3100”)is shown and includes a laptop computer 3130 configured to run LabVIEWsoftware, a RF synchronization module 3190 (e.g., the NationalInstruments USB-6009 data acquisition (DAQ) device), shutter drivers3180, excitation source 3165 (e.g., laser diodes 375 nm and 405 nm,shutters, collimation optics), spectrometer 3150 (e.g., Ocean Optics'USB4000-FL) for emission registration, excitation fiber 3172, andemission fiber 3171. System 3100 may include additional, fewer, ordifferent components than shown in FIG. 31, depending upon a particularpurpose or to achieve a desired result. For example, system 3100 mayalso include laser power supplies and TEC drivers, which are not shownin FIG. 31.

In an experiment conducted using the real-time multi-wavelengthlaser-induced fluorescence spectroscopy system 3100, when bowel wasfixed into the surgical instrument (e.g., surgical instrument 2810 shownin FIG. 28), before the beginning of fusion, the reference laser-inducedfluorescence spectra at excitation wavelengths 375 nm and 405 nm weremanually registered. When RF current (e.g., generated by the RFgenerator 2840 shown in FIG. 28) was applied to tissue, fluorescencespectra at different excitation wavelength were alternately registeredwith a temporal resolution of approximately 300 ms. Following the end ofRF delivery to the tissue, the spectral data acquisition was continuedfor a further six seconds. The aim of this post-RF acquisition was topermit estimation of the fluorescence signal recovery as a possiblediagnostic parameter of the completeness of bowel fusion.

Examples of registered in vivo time profiles of fluorescence intensityat 405 nm for both excitation wavelengths and for different RF fusionprotocols are shown in FIGS. 29A through 30C. Data shown in FIGS. 29Athrough 30C are obtained at the same tissue point during the same RFsealing cycle.

FIGS. 29A through 30C illustrative the fluorescence intensity versustime obtained for excitation wavelength 375 nm (FIGS. 29A, 30A) and 405nm (FIGS. 29B, 30B), as well as the signal from the RF generator output2840 (FIGS. 29C, 30C). FIGS. 29A-C present data registered for RF withparameters dz/dt ramp 0.01 ohms/ms, end impedance 100 ohms. For theexample shown in FIGS. 29A-C, the duration of RF energy delivery fortissue sealing is approximately 10-12½ seconds.

FIGS. 30A-C show data registered for RF delivery with parameters dz/dtramp 0.005 ohms/ms, end impedance 100 ohms. For the example shown inFIGS. 30A-C, the seal cycle is approximately 20-25 seconds.

Every point on the graphs depicted in FIGS. 29A-B and FIGS. 30A-Bpresents the fluorescence intensity, registered at 540 nm. The black boxat time <0 presents fluorescence intensity registered manually justbefore RF energy was applied. At the time point “0” RF energy is appliedand the signal on the servicing output of RF generator is changes from1.3 V “OFF” to 4.5 V “ON” (FIG. 29C, FIG. 30C). Acquisition commencesand fluorescence intensity is registered synchronously to shutters 2861and 2862 (FIG. 28), opening approximately every 300 ms. When RF fusionis finished, RF energy delivery is switched off and the synchronisationsignal is changed to 1.4 V (OFF). Fluorescence acquisition is continuedfor a fixed time period after RF energy delivery is terminated (6seconds in the examples shown). After RF energy is switched off, somefluorescence intensity recovery was observed. Fluorescence intensity isnoted to decrease by approximately 30% at the end of tissue fusion.

A method of treating tissue in accordance with an embodiment of thepresent disclosure includes positioning an end-effector assembly 100(FIG. 1) including first and second jaw members 110 and 120 at a firstposition within tissue. The first and second jaw members 110 and 120include tissue-contacting surfaces 112 and 122, respectively. At leastone of the first and second jaw members 110 and 120 is movable from aspaced relation relative to the other jaw member to at least onesubsequent position wherein the tissue-contacting surfaces 112 and 122cooperate to grasp tissue therebetween. The method also includesactivating a light-emitting element associated with one or both of thefirst and second jaw members 110 and 120 to emit light into tissue andevaluating one or more characteristics of the tissue based on a responseto light entering the tissue. In some embodiments, evaluating the one ormore characteristics of the tissue includes evaluating laser-inducedtissue fluorescence spectra, e.g., using the real-time multi-wavelengthlaser-induced fluorescence spectroscopy system 3100 (FIG. 31).

Although embodiments have been described in detail with reference to theaccompanying drawings for the purpose of illustration and description,it is to be understood that the disclosed processes and apparatus arenot to be construed as limited thereby. It will be apparent to those ofordinary skill in the art that various modifications to the foregoingembodiments may be made without departing from the scope of thedisclosure.

What is claimed is:
 1. A medical instrument comprising: an end-effectorassembly including a first jaw member and a second jaw member pivotablycoupled to each other, at least one of the first jaw member or thesecond jaw member movable from a first position wherein the first andsecond jaw members are disposed in spaced relation relative to oneanother and defining an angle therebetween to at least a second positioncloser to one another wherein the first and second jaw members cooperateto grasp tissue therebetween; at least one light-emitting elementcoupled to at least one of the first jaw member or the second jawmember, the at least one light-emitting element adapted to deliver lightenergy at a plurality of wavelengths to the tissue grasped between thefirst and second jaw members; at least one light-detecting elementconfigured to generate a plurality of fluorescence spectra indicative oftissue fluorescence at the plurality of wavelengths; and a controllerconfigured to receive the plurality of fluorescence spectra anddetermine properties of a tissue seal based on a difference between twoor more spectra of the plurality of fluorescence spectra.
 2. The medicalinstrument according to claim 1, wherein at least one of the first jawmember or the second jaw member includes a groove defined therein havinga reflective surface.
 3. The medical instrument according to claim 2,wherein the at least one light-emitting element is disposed within thegroove.
 4. The medical instrument according to claim 1, furthercomprising an optical assembly coupled to the at least onelight-emitting element, the optical assembly configured to convey lightenergy emitted from the at least one light-emitting element to thetissue and to illuminate the tissue with a desired illumination pattern.5. The medical instrument according to claim 4, wherein the opticalassembly includes at least one of an optical fiber, a refractiveelement, a reflective element, a diffracting element, or combinationsthereof.
 6. The medical instrument according to claim 1, furthercomprising a first electrically-conductive tissue-contacting surfaceassociated with the first jaw member and a secondelectrically-conductive tissue-contacting surface associated with thesecond jaw member, wherein one of the first electrically-conductivetissue-contacting surface or the second electrically-conductivetissue-contacting surface functions as an active electrode and the otherone of the first or the second electrically-conductive tissue-contactingsurfaces functions as a return electrode during activation such thatelectrical energy flows from the active electrode through tissuepositioned between the first electrically-conductive tissue-contactingsurface and the second electrically-conductive tissue-contacting surfaceto the return electrode.
 7. The medical instrument according to claim 6,wherein at least one of the electrically-conductive tissue-contactingsurfaces includes a reflective element configured to reflect lightenergy passing through the tissue.
 8. The medical instrument accordingto claim 1, wherein the end-effector further includes an angle sensordisposed in at least one of the first jaw member or the second jawmember, the angle sensor configured to measure the angle between thefirst jaw member and the second jaw member; and the controller beingcoupled to the at least one light-emitting element and the angle sensor,the controller further configured to adjust intensity of light energyemitted based on the angle.
 9. A medical instrument, comprising: anend-effector assembly including a first jaw member and a second jawmember pivotably coupled to each other, at least one of the first jawmember or the second jaw member movable from a first position whereinthe first and second jaw members are disposed in spaced relationrelative to one another and defining an angle therebetween to at least asecond position closer to one another wherein the first and second jawmembers cooperate to grasp tissue therebetween; at least onelight-emitting element coupled to at least one of the first jaw memberor the second jaw member, the at least one light-emitting elementadapted to deliver light energy at a plurality of wavelengths to thetissue grasped between the first and second jaw members; and acontroller configured to control electrical energy delivered to thetissue disposed between the first and second jaw members and determineproperties of a tissue seal based on a difference between a plurality offluorescence spectra obtained in response to the light energy deliveredat the plurality of wavelengths.
 10. The medical instrument according toclaim 9, further comprising at least one light-detecting elementconfigured to generate one or more signals indicative of the state ofcollagen in the tissue.
 11. The medical instrument according to claim10, wherein the controller is coupled to the at least onelight-detecting element.
 12. The medical instrument according to claim9, wherein the end-effector includes an angle sensor disposed in atleast one of the first jaw member and the second jaw member, the anglesensor configured to measure the angle between the first jaw member andthe second jaw; and the controller is coupled to the at least onelight-emitting element and the angle sensor, the controller furtherconfigured to adjust intensity of light energy emitted based on theangle.